Complete Book_merged.pdf.mmmmmmmmmmmmmmm

Environmental Chemistry

2. Modern
Research and
Environmental
Sustainability

Volume - 3




Chief Editor
Dr. Prachi Parmar Nimje
Associate Professor
HOD (Department of Chemistry)
Shri Shankaracharya Professional University
Bhilai, Chhattisgarh, India










AkiNik Publications
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Publication Year: 2023
Pages: 130
ISBN: 978-93-5570-636-2
Book DOI: https://doi.org/10.22271/ed.book.2202
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4. Contents

Chapters Page No.
1. Nanotechnology Applied in Development of LED Lights 01-16
(Dr. Nidhi Tiwari)
2. Multifaceted Applications of Hydroxamic Acids 17-33
(Dr. Nidhi Tiwari)
3. Nano-Bioremediation: A Boon for Environment 35-49
(Dr. Sangita Devi Sharma and Dr. Kaushilya Sahu)
4. Fluoride in Water-Cause, Health Risk and Removal Studies 51-64
(Dr. Meena Chakraborty and Dr. Manisha Thakur)
5. Status of Coral Reefs, their Ecological Value and
Conservation Management 65-78
(Ranjeet Singh, Anurag Semwal and Neelesh Kumar)
6. Grindstone Reactions as a New Green Chemical Approach 79-95
(Dr. Maher Mohamed Abed El Aziz)
7. Range Over on Brute Creation white Tigers along with others
of Maitri Baag Zoo Bhilai, Chhattisgarh 97-112
(Roli Ojha Mishra)
8. Succession of Cable Bacteria and Its Biogeochemical Impact
in Marine Sediments 113-130
(Apoorva D, Vishwanatha T* and Keshavamurthy M)

6. Page | 1
Chapter - 1
Nanotechnology Applied in Development of LED
Lights



Author
Dr. Nidhi Tiwari
Associate Professor, Chemistry, Shri Shankaracharya
Professional University, Junwani, Bhilai, Chhattisgarh, India

7. Page | 2

8. Page | 3

Chapter - 1
Nanotechnology Applied in Development of LED Lights
Dr. Nidhi Tiwari


Abstract
LED lights are the most common type of lighting. LED lights save a lot
of electricity and have a longer shelf life than a regular bulb or tube light.
Modern technology is used to create economically and environmentally
friendly products for modern life. The chapters discuss the use of
nanotechnology in the development of LED lights, which are still being
researched for the development of environmentally friendly technology. As
you are aware, electricity is used to power light bulbs, and electricity
production is based on thermal power plants, hydroelectric plants, and nuclear
energy. Electricity consumption can be reduced by introducing new
technology such as LED bulbs, tube lights and other types of lighting, among
other things. Nanotechnology is a growing field.
Keywords: Nanoscale, nanowires, nanoscience, nanotechnology, nanolayer
Introduction
Nanotechnology and research in this field are becoming increasingly
popular. The newly emerging field of Nanoscience and nanotechnology are
ushering in a new millennium technological revolution. Nanotechnology has
enormous potential to significantly influence the world in which we live
[1]
.
Nanotechnology will have a significant impact on all sectors of the economy,
including consumer goods, electronics, computers, information and
biotechnology, as well as aerospace defence, energy, the environment and
medicine. Several research initiatives have been undertaken in the United
States, Europe, Australia, and Japan by both government and private sector
members to accelerate research and development in nanotechnology. The
prefix nano' refers to a billionth. Nanometers are one billionth of a metre (10
-
9
metre).
Consider a flat conducting plate of great length and width and small
thickness. Assume that the plate is nanometers thick. In this case, the electron
is limited along one dimension, but moves freely along the other two

9. Page | 4
dimensions
[2]
. This phenomenon is known as “quantum wells". Consider a
conducting wire that has a long length, but the diameter of the wire is very
small. In this case, electron is free to move along the length, but is constrained
to be mutually perpendicular to the other two
[3]
. This configuration is called
"quantum wire". If all three dimensions of the conductor are in the nanometer
range, the electron is confined in all three dimensions. This configuration is
known as a "quantum dot”.
Table 1
Year Remarks Country/People
1200-1300 BC Discovery of soluble Gold Egypt and China
295-325 AD Lycurgus cup Alexandria and Rome
1618 First book on Colloidal Gold F. Antonii
1676
Book Published on Drinkable
Gold that contains metallic
gold in neutral media
J. Von Lovenstern-Kunckel (Germany)
1718
Publication of complete
treatise on colloidal gold
Hans Heinrich Heicher
1857
Synthesis of colloidal gold M. Faraday (The Royal Institution of
Great Britain)
1902
Surface plasmon resonance
(SPR)
R.W. Wood (John Hopkins University,
USA)
1908
Scattering and absorption of
electromagnetic field by a
Nanosphere
G. Mie (University of Gottingen,
Germany)
1931
Transmission Electron
Microscope (TEM)
M. Knoll and E. Ruska (Technical
University of Berlin, Germany
1937
Scanning Electron
Microscope (SEM)
M. von Ardenne (Forschungs
laboratorium fur Elektronen-physik,
Germany)
1959
Feynman’s Lecture on
“There’s Plenty of Room at
the Bottom”
R.P. Feynman (California Institute of
Technology, Pasadena, CA, USA)
1960
Microelectromechanical
Systems (MEMS)
I. Igarashi (Toyota central R&D Labs,
Japan)
1960
Successful Oscillation of a
Laser
T.H. Malman (Hughes Research
Laboratories, USA)
1962 The Kubo effect R. Kubo (University of Tokyo, Japan)
1965
Moore’s Law G. Moore (Fairchild Semiconductor
Inc., USA)
1969
The Honda-Fujishima effect A. Fujishima and K. Honda(University
of Tokyo, Japan)
1972 Amorphous heterostructure E. Maruyama (Hitachi Co. Ltd. Japan)

10. Page | 5
photodiode created with
bottom-up process
1974
Concept of Nanotechnology N. Taniguchi (Tokyo University of
Science, Japan)
Source: Table 1.2, Chronological role of Nanotechnology, Page no 6, 1. Introduction
to Nanoparticles
Modern industrial nanotechnology had its origins in the 1930s, in
processes used to create silver coatings for photographic film; and chemists
have been making polymers, which are large molecules made up of nanoscale
subunits, for many decades. However, in the ninth century during the Abbasid
dynasty is when the nanoparticles were first documented to have been used.
Arab potters used nanoparticles in their glazes so that objects would change
colour depending on the viewing angle (the so-called polychrome lustre)
[4]
.
Today’s nanotechnology, i.e. the planned manipulation of materials and
properties on a nanoscale, exploits the interaction of three technological
streams 5:
1) Enhanced and unprecedented control over nanoscale building block
size and manipulation.
2) Novel and enhanced nanoscale characterization of materials (e.g.,
chemical sensitivity, spatial resolution).
3) New and enhanced knowledge of the connections between
nanostructure and characteristics, as well as the engineering of these.
Nano tools and fabrication techniques Legend has it that the people who
profited most from the Klondike gold rush at the end of the 19th century were
the sellers of picks and shovels. The same may hold true for nanotechnology,
at least in the coming decade before production techniques are improved. The
$245 million nanotech tools market will expand by 30% yearly over the
following few years, predict market experts Freedonia. Microscopes and
related tools dominate now, but measurement, fabrication/production and
simulation/modelling tools will grow the fastest. Electronics and life sciences
markets will emerge first; industrial, construction, energy generation and other
applications will arise later.
Electronics and communications: Wireless technology, flat-panel
displays, nanolayer and dot recording, new equipment and procedures
throughout the full spectrum of information and communication technologies,
factors of thousands to millions improvements in both data storage capacity
and processing speeds and at lower cost and improved power efficiency
compared to present electronic circuitsLight emitting diodes are characterized
by these advantages, small size, low heat emission, long life and high light

11. Page | 6
output. Light-emitting diodes (LEDs) have many advantages for industrial
applications, such as smaller volume and lighter weight.
Heat dissipation, power consumption, long life, quick response. LEDs are
widely used
Indicator lights, signal lights, large backlight modules, etc(5-7)His IEK
report for ITRI states, White LEDs are gradually introduced into the lighting
market, and the output value of white LEDs reaches 1.6US$1 billion in 2012
[8]
. When packaging an LED bulb, the first requirement is a special optical lens
that covers the LED chip. Of generally, the light divergence angle of a
particular lens should be designed between 120 and 160 degrees, but the LED
is brighter in the center. Therefore, it should be covered by a second optical
lens to achieve a uniform display. It has high luminosity and meets lighting
requirements
[9]
. To meet diverse lighting requirements, The LEDs have
different array type layouts. LED lamps are composed of multiple LED chips
and induce glare and multiple shadows of the object under illumination
[10]

(LEDs) are widely used in diversified lighting in recent years. However, LEDs
have a higher light intensity. Due to scattering in the central area and
environment during lighting, the LED projection needs to be
changed.secondary optical lens. Adding an auxiliary optic lens can improve
the light collection efficiency of the LED, and that will soon be the case. It
causes multi-shadow phenomenon when lighting and has a great impact on
human vision.
How led lights are made?
LED lighting, like incandescent and fluorescent lighting, not only differs
in design, but also in light production. Traditional lighting creates light by
connecting wires to a power source. When the wire gets hot, it gives off light.
LEDs produce light through electronic excitation rather than heat. Because of
this, LEDs consume less energy and emit less heat, as heat is not the dominant
factor in light generation.
LED Materials
LED stands for Light Emitting Diode. LED lights are therefore made up
of tiny diodes. Each diode is made of semiconductor material. One layer of
semiconducting material becomes electron-rich and one layer is electron-
depleted. This electronic level difference causes electrons to move from one
layer to the next, producing light through the aforementioned electronic
excitation. In a little more detail, semiconductor materials themselves are
made of crystalline materials and require impurities to conduct electricity.
However, these impurities are added to the semiconductor material later in the
manufacturing process.

12. Page | 7
However, these impurities should not be confused with defects in
semiconductor materials. Don't lower the value of diodes, raise the value!
Adding these impurities to semiconductors is called doping, and they are
essential materials in the manufacture of LEDs. The most commonly added
impurities are zinc and nitrogen.
Finally, we need to add a wire to power the diode. Gold and silver
compounds are commonly used for LED wires because they are suitable for
soldering and heating. Additionally, the diodes are encased in clear plastic
rather than glass like traditional incandescent bulbs, making them durable and
long-lasting.
LED Design
You can be a little more creative when designing LED lights. The color
temperature, brightness and efficiency are decided according to the purpose
of the light, and then manufactured. These attributes are set based on the size
of the diode, the semiconductor material used, the type of impurities added,
and the thickness of the diode layers.
LED manufacturing is a delicate and complex task, but I'll do my best to
summarize. First, the semiconductor material must be prepared. This is called
a semiconductor wafer. Semiconductor materials are "grown" in a high
temperature and pressure chamber. Elements such as gallium, arsenic, and/or
phosphorus are cleaned and mixed in the chamber and liquefied into a
concentrated solution. Once the elements are mixed, place the stick into the
solution and slowly pull it out. When the rod is pulled out, the solution
crystallizes at the end of the rod, creating long cylindrical crystal blocks.

13. Page | 8

Fig 1
Manufacturing
This material is then cut into semiconductor wafers and ground until the
surface is smooth, essentially the same as grinding a table. It is then immersed
in a solution of various solvents for a thorough cleaning to remove dirt, dust,
or organic matter.Further layers of semiconductor material are added to the
wafer in the next process step. This is one method of adding impurities or
dopants. A metal contact is then defined on the semiconductor. This is
determined at the design stage, considering whether the diode is used alone or
with other diodes. Finally the diode is mounted in a suitable housing, the wires
are attached and everything is covered in plastic
[11]
.

14. Page | 9

Fig 2
Nanotechnology used in led lights
Due to their widely tunable wavelength from ultraviolet to blue/green
(12), gallium nitride-based light emitting diodes (GaN-based LEDs) have been
widely used in a variety of applications over the last decade, including back-
lighting sources in display systems, traffic signals, and outdoor displays. Most
importantly, they have the potential to replace incandescent or fluorescent
lighting. For general lighting, fluorescent mercury (Hg) and xenon (Xe) lamps
are used. To accomplish this, the external quantum efficiency (EQE) of LEDs
should be improved further.Essentially, the EQE is the product of extraction
efficiency and internal quantum efficiency (IQE).In terms of extraction
efficiency, the critical angle of light extraction is approximately 23° due to the
large refraction index difference between GaN (nGaN=2.5) and air (nair=1).
As a result, only a small percentage of the generated light can be extracted
from the surface, limiting the extraction efficiency. Several works, including
surface roughening
[13]
inclined sidewalls
[14]
use of photonic crystals4, and
diffused mirror techniques
[15]
, have been developed to improve extraction
efficiency. Furthermore, one issue with traditional GaN-based LEDs is the
sapphire substrate's poor thermal conductivity. As a result, a GaN-based
vertical LED with laser lift-off (LLO) and waferbonding to another substrate
with good thermal conductivity was developed.

15. Page | 10
The epitaxial lateral overgrowth (ELO) method with a microscale SiNx
or SiOx patterned mask on as-grown GaN seed crystals has been shown to
effectively reduce the threading dislocation density (TDD)
[16]
and improve the
IQE. However, the two-step growth procedure requirements and a sufficient
thickness for GaN coalescence is both expensive and time consuming.
Furthermore, wet etching was used to demonstrate high quality GaN-based
LEDs on a microscale patterned sapphire substrate (PSS)
[17]
where the
microscale patterns served as a template for the ELO of GaN and the scattering
centres for the guided light. Both epitaxial crystal quality and light extraction
efficiency were improved. The PSS structures can then be scaled down to the
nanoscale.

Fig 3: Fabrication Schematics of a GAN-InGAN VI LED, (a) the epitaxial structure
(b) Water Bonding & LLO Processes (c) Nanorod Fabrication involving Self-
assembled silica spheres as lithographic and Etch masks, and (d) the fabricated
device Schematic

16. Page | 11

Fig 4: Field-emission Scanning-electron micrographs (FE-SEM) of (a) the densely
packed silica spheres on GaN, Showing a mean diameter of 100nm with a uniformity
better than 1% (b) Cross-sectional view of the fabricated nanorods with a base
diameter of 200nm & a height of 1.3μm similar to cone structure (c) Voltage & light
output intensity versus forward current characteristics for a conventional GaInGaN
VI-LED without nanorods & the VI-LEDs with nanorod arrays

Fig 5: (a) Measured & Stimulated emission profiles of a GAN-InGaN VI-LEDs with
and without nanorod arrays, where the snapshots of stimulated wave propagation are
shown in (b) & (c) respectively

17. Page | 12
Metallic nanostructures for efficient LED lighting
Solid-state lighting (SSL) is a lighting technology that has emerged in the
last decade as a result of the development of white light-emitting diodes
(LEDs). LEDs currently employ a mature technology
[18]
. Because of their
higher efficiencies, longer lifetimes, fast switching, robustness, and compact
size, LEDs outperform traditional light sources
[19-20]
. LEDs operate on the
basis of electroluminescence, or the radiative recombination of injected
electron-hole pairs in a material. Round3 discovered electroluminescence in
inorganic semiconductors by applying a voltage across two contacts on a SiC
crystal to generate yellow light. Electroluminescence was extensively studied
in the years that followed4 and was reported in several III-V semiconductors
in the 1950s9
[21-22]
. Techniques for creating p-n junctions improved as well,
resulting in the demonstration of infrared and red light.
Nanostructures with dimensions comparable to light wavelengths are
particularly well suited to enhancing light-matter interactions. In this regard,
metal surfaces and nanostructures that support surface plasmon polarization
(SPP) resonance are of particular interest
[23]
. These resonances are due to the
coherent vibration of the charge carriers in the metal. SPPs have the ability to
modify spontaneous emission from sources near metals, thereby influencing
emission rate and directionality
[24-33]
. These changes are similar to antenna
resonant amplification and directional radiation. As a result, metallic
nanoparticles that support SPPs have been dubbed optical antennas or
nanoantennas. However, incorporating such resonant nanostructures into
advanced lighting applications remains challenging. The vast majority of
studies have concentrated on modifying the emission properties of single
and/or multiple.
Organic led lights based on nanotechnology
Light-emitting diodes, now found in everything from traffic lights,
taillights and mobile phone displays to stadium jumbotrons, fluoresce when
an electric current is passed through them. The most advanced LED
technology is based on crystals, usually made of indium gallium nitride. But
researchers at ORNL's Center for Nanophase Materials Science and the
University of Tennessee are developing techniques to improve a new
generation of LEDs made from thin films of polymers or organic molecules.
These organic LEDs are formed into thin, flexible sheets that promise a
new generation of lighting and flexible electronic displays. Applications of
organic LEDs or OLEDs are currently limited to small-screen devices such as
mobile phones, personal digital assistants and digital cameras. However, there

18. Page | 13
is hope that one day it will be possible to make large displays and lamps using
inexpensive manufacturing methods.
At ORNL, researchers are developing carbon nanotube and magnetic
nanowire electrodes to improve the emission of polymer-based OLEDs. In
previous experiments, carbon nanotubes improved the electroluminescence
efficiency of polymer OLEDs by a factor of four and reduced the energy
required for operation.
Magnetic nanowires and dots have been shown to control the spin of
electrons injected into OLEDs to further improve device efficiency and
reliability. His third aspect of research focuses on the fabrication and chemical
processing of the nanotubes themselves, with researchers at ORNL using laser
deposition and laser deposition to produce purer nanotubes with fewer defects
than other fabrication techniques. Using a technique called laser vaporization
produces purer nanotubes with fewer defects than other fabrication
techniques.
Conclusion
Nanotechnology significantly changed the characteristics about physical
and chemical. Solid physical material properties such as electrical
conductivity, magnetism, fluorescence, hardness or the intensity changes
radically. Chemical reactivity so high that the material breaks down Partial
structures up to the nano-scale appear strongly. Increased ratio of reactive
surface atoms to inert particles tight with a particle of diameter 20nm, say
about 10% of the atoms are on surface, whereas for 1 nm particles reactive
surface atoms are already 99%. Using a new nano-scale structure by the
researchers in field of electrical engineering increased the brightness and
efficiency of LEDs made of organic materials (flexible carbon-based sheets)
by 57 percent. The researchers also report their method should yield similar
improvements in LEDs made in inorganic (silicon-based) materials used most
commonly today.
An OLED is a device that emits light when an external voltage is applied.
Nanocomposite materials are classified into two types: nanostructured
composites with a structure of nanoparticles embedded in polymers
(abbreviated NIP) and nanocomposites with a structure of polymers deposited
on nano-porous thin films (abbreviated PON). Organic electroluminescent
materials and devices have made significant advances in terms of synthesis,
development, and application of electron transport materials as a means of
improving OLED performance. Three critical processes govern the
effectiveness of an OLED device: charge injection, charge transport, and

19. Page | 14
emission. Various layers in the organic stack are dedicated to one of the three
processes listed above, such as surface modification in the Hole Injection
Layer and Electron Injection Layer, high temperature in the Electron Injection
Layer and high temperature in the Electron Injection Layer. This leads to
development of cheap and long lasting devices which is economically and
environmental friendly.
References
1. Adleman L. Molecular computation of solutions to combinatorial
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3. Barett JT. (N.D.) Examples of nanotechnology applications in electronics.
http://science.opposingviews.com/examples-nanotechnology-
applications-electronics-18240.html
4. Baughman RH, Zakhidov AA, Heer WA. Carbon nanotubes-the route
toward applications. Science’s Compass, 2007.
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002.pdf
5. Koike M, Shibata N, Kato H, Takahashi Y. Development of high
efficiency GaN-based multi-quantum-well light-emitting diodes and their
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6. Bando K, Sakano K, Noguchi Y. Development of high-bright and pure-
white LED lamps, Journal of Light & Visual Environment. 2008;22(1):2-
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7. Muqing Liu, Bifeng Rong. Evaluation of LED application in general
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8. Meng-Jiao Huang, Global LED. Lighting industry of market conditions
And Trend Analysis, ITRI’s Newsletter, 2007, 97-10.
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uniform illumination, Optics Express. 2008;16(17):12958-12966.
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11. https://sitlersledsupplies.com/how-are-leds-made/)
12. Nakamura S, Fasol G. The Blue Laser Diode, Springer, New York, 1997.

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20. Schubert EF, Kim JK. Solid-state light sources getting smart. Science.
2005;308:1274-1278.
21. Tsao JY, Crawford MH, Coltrin ME, Fisher AJ, Koleske DD, et al.,
Toward smart and ultra-efficient solid-state lighting. Adv. Opt. Mater.
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22. Round HJ. A note on carborundum. Electr World. 1907;49:308.
23. Losev OV. Luminous carborundum detector and detection with crystals.
Telegr Telef Prov. 1927;44:485-494.
24. Wolff GA, Hebert RA, Broder JD. Electroluminescence of GaP. Phys
Rev. 1955;100:1144-1145.
25. Braunstein R. Radiative transitions in semiconductors. Phys. Rev.
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26. Holonyak Jr. N, Bevacqua SF. Coherent (visible) light emission from
Ga(As1-xPx) junctions. Appl. Phys. Lett. 1962;1:82-83.
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30. Nakamura S, Mukai T, Senoh M. Candela‐class high‐brightness
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22. Page | 17
Chapter - 2
Multifaceted Applications of Hydroxamic Acids



Author
Dr. Nidhi Tiwari
Associate Professor, Department of Chemistry, Shri
Shankaracharya Professional University, Junwani, Bhilai,
Chhattisgarh, India

23. Page | 18

24. Page | 19

Chapter - 2
Multifaceted Applications of Hydroxamic Acids
Dr. Nidhi Tiwari


Abstract
Many hydroxamic acids are present are present in nature as well as they
are synthesized. Most of them are N-substituted variety which have been
reported by many Scientists. Various Substituted hydroxamic acids such as N-
Phenyl-2-methylbenzohydroxamic acid, N -Phenyl 4 -
ethoxybenzohydroxamic acid, N-o-tolyl-2-methylbezohydroxamic acid, N-o-
Tolylphenoxyacetohydroxamic acid etc. have been prepared in laboratory
whereas hydroxamic acid such as 2,4-dihydroxy-7-methoxy-(2H)-1,4-
benzoxazin-3(4H)-one(DIMBOA) present in corn roots, Aspergillic Acid is
Pyrazine cyclic hydroxamic acid was found to be present in Aspergillus
flavus, 2 -amino-N-(2-amino-3-phenylpropanoyl)-N-hydroxy-3-
phenylpropanamide, a novel hydroxamic acid containing molecule is present
in bacteria Streptomyces has antimicrobial property, 4-Hydroxy-1,4-
Benzoxazin-3-ones in Graminae. Because of their wide applications in various
fields such as Agriculture, analytical, biological, Technical and nuclear
chemistry etc.
Keywords: Extractants, antiviral, anticancer agents, metal ion chelators
Introduction
Hydroxamic acids, the versatile metal extractants, have exhibited many
interesting facets of chemistry since these were first reported by H. Lossen in
1869
[1]
. The chemistry of hydroxamic acids is complex and offers a fruitful
area of research both from academic and practical considerations. Extensive
work has been carried out on their formation, reactions and structure on
ground state. These reagents possess a wide spectrum of activities in various
fields of agriculture, analytical, biological, technical and nuclear chemistry
and are products of some photochemical reactions. Hydroxamic acids have
received wide attention among analytical chemists because of their ability to
form highly coloured metal ion complexes. There is renewed biochemical
interest in hydroxamic acids as a result of finding this characteristic group in

25. Page | 20
natural products. Hydroxamic acids, the naturally occurring and synthetic
products, generally have low toxicities and are of interest for many therapeutic
applications. Novel hydroxamic acid intermediates have been reported to be
active as herbicides and pesticides.
History and Nomenclature
The pioneer work on these versatile metal extractants, was done by H.
Lossen. Hydroxamic acids, are the N-acyl derivatives of hydroxylamine,
which can exist in tautomerism with enol form, named as hydroximic acid, II.
The keto form predominates in the acid medium and the enol form in alkaline
medium.

I II
With the discovery of hydroxamic acids, a new functional group was
introduced in the field of organic chemistry, known as hydroxamic acid
functional group, III,

III
Which is the outstanding chemical feature of these molecules. Structure,
I, represents the unsubstituted hydroxamic acids. When aryl, alkyl or cyclic
group replaces the H-atom attached to N-atom in I, then N-substituted
hydroxamic acid, IV, is formed.

IV
N-acylation occurred in all cases under different conditions as well as
with various acylating agents.
Bamberger in 1919
[2]
laid the foundation of N-aryl substituted
hydroxamic acids by synthesizing N-Phenylbenzohydroxamic Acid, V, trivial
name PBHA.

26. Page | 21

V
Substituted hydroxamic acids are incapable of exhibiting tautomerism.
Although PBHA was synthesized as early as in 1919, it came to the fore when
Shome
[3]
introduced it as an analytical reagent for copper (II), iron (III),
aluminium (II) and titanium (IV). Thereafter, a large number of analogues of
PBHA have been synthesized
[4-21]
and today a rapidly growing literature on
them is available. A number of review articles, monographs and textbooks
deals with the chemistry of hydroxamic acids. Several aspects, namely their
synthesis, nomenclature, rearrangement, physical and chemical properties,
structure and applications are reviewed from time to time
[22-27]
. The physico-
chemical problems involved in the field, viz., ionisation and complexation
equilibria, tautomerism, configuration, conformation and spectral behaviour
are also excellently reviewed
[28-33]
.
Hydroxamic acids in nature
Isolation of naturally occuring hydroxamic acids enhanced the progress
in hydroxamic acid chemistry. Aspergillic acid, VI, was the first naturally
occurring hydroxamic acids. This

VI
hydroxamic acids bond also occurs in Products from fungi, yeast, bacteria
and green plants. Ferrichrysin and ferrichrome are found in Japanese sake and
account for part of its yellow colour of that beverage
[34]
. Those which are
present in Penicillium griseofulvum and fusarinine, serve as antibiotics
[35]
.

27. Page | 22
These are also the products of some photochemical reactions
[22]
. Some
xenobiotic and natural substances contain hydroxamic acids which forms
reactive acyl aminoxyl radical intermediates as a result of photochemical
reactions are found to cause cancer
[36, 37]
for characterisation of natural
hydroxamic acids, periodic acid is useful which selectivel cleaves the
hydroxamic acid linkage while amide and other even more sensitive bonds
remain unaffected.
Applications
These metal extractants covered a very wide range of applications as
follows-
1. Agricultural applications
Many synthetic hydroxamic acids such as Cyclic hydroxamic acids, 2,4-
dihydroxy-1,4-benzoxazin-3-one (DIBOA) have been reported to be active as
plant growth promoters
[36]
and as soil enhancers
[38]
. Hydroxamic acid present
in the side chain of amino acids are found to be the inhibitors of the root
growth in Lettuce Seedlings
[39]
. These are also found to be present in rye plant
and gramineae
[40, 41]
and are used as cultivators in corn seedlings to reduce
water potentials during and after germination
[42]
. These are used in alternating
benzohydroxazinone levels in plants which act as plant defence mechanism
for insect and disease resistance and for increasing herbicide tolerance
[43]
.
These reagents are used in breeding for aphid resistance in wheat, maize and
rye plants
[44, 45]
.
2. Analytical applications
Hydroxamic acids and their N-arylsubstituted derivatives, serve as
effective metal ion chelators. These resultant complexes are highly coloured
and therefore, useful in colorimetric analyses of metal ions
[24, 46-59]
or
hydroxamic acids
[60]
. Crown’ hydroxamic acids
[57, 58]
are used for the
estimation of Lanthanum (III) and Copper (II). Metal ligand complexes have
also been extracted, involving hydroxamic acid as primary ligand and
histamine or the glycine and histidine as secondary ligands
[61]
. Hydroxamic
acid HGS 98 is involved in extraction separation of Germanium
[62]
. Cerium-
polyhydroxamic acid resin complex act as chelating ion exchanger for
removal of fluoride ion from aqueous solution
[63]
. Bis-hydroxamate complex
of Rhodium(III) and oxidation of Rhodium (I) by hydroxamic acids is reported
recently
[64]
. Vernon and Eccles (1976) and Sharma et al. (2013) reported that
poly(hydroxamic acid) chelating resin can be used for extraction of iron from
various salts
[65-66]
. Hassan et al. (2011) reported that polyhydroxamic acids
are useful for separation of Zr (IV) from Y (III) and Sr (II) and purification of

28. Page | 23
Zr
[67]
. Gidwani et al. (2009) reported that a new chromogenic calixarene with
hydroxamic acid acts as chelating agent for sequential separation of Ti (IV)
and Zr (IV)
[68]
.
3. Biological applications
Hydroxamic acids, their derivatives and metal complexes performed a
broad spectrum of Biological activities
[17, 18, 69-74]
. Most of them are
antimicrobials
[75-82]
. Agrawal et al.
[83]
has reported the synthesis and
characterization of Hydroxamic Acids Such as N-Phenylbenzo hydroxamic
Acids (N-PBHA), N-p-Tolyl benzohydroxamic Acids (OTBHA), N-p-Tolyl
benzohydroxamic acids (PTBHA), N-m-Chlorobenzo Hydroxamic Acids
(MCBHA), N-p-Carboxyphenylbenzo Hydroxamic Acid(PCBHA), Aceto
Hydroxamic Acid(AHA), benzohydroxamic Acid (BHA), Salicyl
Hydroxamic Acid(SHA). Antagonists
[84]
, antibacterial
[74, 84-86]
, anticancer
[87-
91]
and antiviral agents
[92-93]
. These are shown for the first time to be effective
NO donors by their ability to readily form ruthenium(Il)-nitrosyls for the
activation of iron-containing guanylate cyclase
[25]
. Dihydroxamic
siderophores have been found to be Effective scavangers of hydroxyl radicals
(OH) responsible for cell damage
[94]
. They are also capable of competing as
siderophores for iron-(III)
[94-96]
. One natural siderophore, deferrioxamine is
still the drug of choice for the treatment of iron overload
[97, 98]
associated with
the trans fusional treatment of B-thalassemia or Cooley's anaemia
[99-103]
.
hydroxamic acids moieties are used in the design of therapeutics targeting
cardiovascular diseases
[124, 105]
, HIV
[106, 107]
, Alzheimer’s
[108, 109]
, allergic
diseases
[110-112]
.
Some hydroxamic acids are potentially useful for the removal of other
toxic metals, including plutonium from biological systems
[113]
. On one hand
these are involved in plant growth regulators
[114-116]
, cell division
[43]
, DNA
biosynthesis
[114, 115]
, iron uptake
[117, 118]
and metabolism
[33, 35]
and on the other
many of them are powerful mutagens. 11 pyridine- and 6 quinoline-
carbohydroxamic acids were tested for mutagenicity on Salmonella
typhimurium TA100 and TA98
[119]
. and carcinogens
[120]
. They also show
important role as urease inhibitors which inhibits stone formation in urinary
tract
[121]
and also inhibits peroxidases
[122]
and matrix metalloproteinases
[123,
124]
, controlling Helicobacter pyroli-induced gastritis
[125]
and display DNA
cleavage properties
[126]
. Many synthetic hydroxamic acids also exhibit
fungicidal, antimalarial, antitumor and antibacterial activities and used for the
treatment of connective tissue degradation
[59, 127-132]
. These are also used as
anti-inflammatory agents and are inhibitors of matrix metalloproteinase,
TNFα secretion, histone deacetylase and carbohydrate metabolism
[131-141]
. N-

29. Page | 24
(1-naphthyl)valerohydroxamic acid (NVHA) and N-(1-
naphthyl)phenylacetohydroxamic acid (NPAHA) behave as antioxidants and
helps in DNA Cleavage protection(A).
4. Technical applications
Amongst the expedient applications, the most significant is the froth
floatation technique
[142, 143]
, where the extraction of metal from the ores are
performed efficiently with hydroxamic acids. These are also used as corrosion
inhibitors
[144-147]
and when used in photography, improves the self-life of
silver halide photographic materials and latent image stability
[148-150]
. Some
substituted hydroxamic acids are applicable as surfactants
[151]
. Some water-
soluble polymers including hydroxamic acid group performed selective
separation of metal ions from aqueous streams or metal from solid matrix
[152,
153]
. Oxalohydroxamic acid is used in combustible compounds as primers for
gun ammunition and other priming powders
[154]
. They are also used
industrially as antioxidants
[115-116, 155-156]
, for the extraction of toxic elements
[157]
, as a means of flotation of minerals
[158, 159]
and even for their ability to
serves as redox switches for electronic devices. A polymer bearing
hydroxamic acid groups and having a high affinity for iron(III) was prepared
and the iron chelating ability of hydroxamic acid polymers was studied.
5. Nuclear applications
Hydroxamic acids are formed as a product during nuclear fuel
reprocessing
[163-165]
are also used for the retention of fission products
especially Zirconium
[166]
. Uranium from nuclear fuel is separated and
recovered using N-Phenylbenzo-18-crown-6-hydroxamic acid
[167]
.
Conclusion
The chemistry of Hydroxamic Acids and their derivatives have received
significant interest because of their pharmacological, toxicological and
pathological properties since 1959 which is the year of discovery of
hydroxamic acids by Wahtroos and Virtanen. Hydroxamic Acids play a vital
role in many biologically related interactions and its derivatives have a variety
of pharmaceutical properties. Hydroxamic acid and its derivatives shows wide
application in various fields as mentioned above. Hydroxamic acid and its
derivatives has ability to chelate metal ions such as Fe(III) and Zn, hydroxamic
acid is one of the most intriguing moieties in medicinal chemistry This ability
is used for the development of various compounds capable of inhibiting
various metalloenzymes such as HDACs, CAs, MMPs, ADAMs, and so on.
Several synthetic approaches have been developed to develop HA-based
compounds, beginning with different functional groups such as carboxylic

30. Page | 25
acids, amides, acyl chlorides, esters, and aldehydes. Their mutagenicity
appears to be influenced by Hydroxamic Acids decoration and/or substitution
with Hydroxamic Acids bioisosters. Importantly, some Hydroxamic Acid
derivatives have reached the market, and others are currently being evaluated
in clinical trials, demonstrating their importance in drug discovery.
Hydroxamic acids' ability to form stable transition metal complexes is the
foundation of their utility as an analytical reagent for sensitive qualitative and
quantitative determinations. In addition to the trace elements Mn, Fe,Co,V,
and Cr, which are essential for many forms of life, there are others, such as
nickel, whose biological role is unknown.
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Chapter - 3
Nano-Bioremediation: A Boon for Environment



Authors
Dr. Sangita Devi Sharma
Department of Botany, Government Naveen College, Bori,
Durg, Funda, Chhattisgarh, India
Dr. Kaushilya Sahu
Rajiv Pandey Government College, Bhatagaon, Raipur,
Chhattisgarh, India

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Chapter - 3
Nano-Bioremediation: A Boon for Environment
Dr. Sangita Devi Sharma and Dr. Kaushilya Sahu


Abstract
Due to human interference ecosystem of all over the world are extensively
contaminated by inorganic and organic contaminants. That represents a threat
to all types of ecosystems. The degradation of these inorganic and organic
contaminants from the environment is a difficult task. Various physical,
chemical and biological methods are implemented for the degradation of
inorganic and organic contaminants from the environment. Now a day
biogenic bioremediation in combination with nanotechnology is the most
promising and cost-effective method for degradation of these contaminants.
These techniques also prevent further contamination of ecosystem. However
more extensive research is needed to utilize this technology in large extent.
Keywords: Nano-bioremediation, inorganic and organic contaminants,
Nanoparticles, nanotechnology, degradation
1. Introduction
“Remediation” means to solve the problem and “bioremediation” means
the process by which various biological agents, such as bacteria, fungi,
protists, or their enzyme are used to degrade the environmental contaminants
into useful or less toxic forms [Dillewijn et al. 2007]. The important benefit
of nanobioremediation over conventional treatments is economical, high
competence, minimization of chemical and biological sludge, selectivity to
specific metals, no supplementary nutrient requirements, regeneration of
biosorbent, and the possibility of metal recovery [Kratochvil and Volesky,
1998]. When nanobioremediation occurs on its own, then it is known as
natural attenuation or intrinsic nanobioremediation and when it is incited to
occur with the addition of fertilizers for the enhancement of bioavailability
within the medium, then it is known as biostimulated nanobioremediation
[Rizwan et al. 2014]. Most common nano-bioremediation technologies
include bioventing, bioleaching, bioreactor, bioaugmentation, composting,
bio-stimulation, land farming, phytoremediation and rhizofiltration [Li and Li
2011].

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2. Types of nano-bioremediation techniques
In the contaminated site nanobioremediation works in two ways. In the
first case various substances such as the light temperature, nutrients and
amount of oxygen are used to enhance the growth of pollution-eating microbes
(indigenous microorganisms) might already be living at the contaminated site.
In the second case, specialized microbes (exogenous microorganisms) were
added to degrade the contaminants. But in both cases if harmful chemicals are
also used for cleaned up and microbes die. For better result
nanobioremediation applications fall mainly into two broad categories: in situ
and ex situ. In situ nanobioremediation is used for the removal of toxic
material in the location in where it is found hence it is less expensive because
in this process there is less release of contaminants, toxin or pollutant to the
environment However, it is slower and some time may be difficult to manage,
whereas ex situ nanobioremediation processes require excavation of
contaminated or toxic substances before they can be treated. Ex situ
techniques can be easier to control and are used to remove a wider range of
contaminants and soil types than in situ techniques [Prokop et al. 2000]
3. Characterstics properties of nanoparticles that leads effective
bioremidiation (Mohsin and Hachim 2014)
Some characteristics properties of small size of nanoparticles leads to
several characteristics that may enhance remediation are:
1) They are small enough to confine their electrons and produce
quantum effects. The term ‘nanoparticles’ is used generally to
describe specifically engineered materials that have at least one
dimension between 1 and 100 nm.
2) Their small particle size also allows nanoparticles to enter small
pores in soil or sediment that larger particles might not penetrate,
granting them access to contaminants absorbed to soil and increasing
the likelihood of contact with the target contaminant (Kern et al.
2009).
3) Nanomaterials are highly reactive because of their high surface
area per unit mass (Kern et al. 2009).
4) Nanoparticles are widely used in various fields such as photonics,
catalysis, electronics and biomedicine due to these unique properties.
5) They reduce site clean up time.
6) They reduce the overall costs of cleaning up large-scale contaminated
site.

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7) This particle is also used for bioremediation of radioactive wastes
like uranium (produced by nuclear power plants and nuclear weapon
production). Example: Cells and S-layer proteins of Bacillus
sphaericus JG-A12 have been found to have special capabilities for
the cleanup of uranium contaminated waste waters (Duran et al.
2007).
4. Remediation, bioremediation and nano-bioremediation
Remediation: Removal or breakdown of contaminants from polluted
soils, surface water or ground water as well as in sediments.
Bioremediation: Use of biological system or microorganism’s to remove
hazardous environmental pollutants.
Nanobioremediation: The use of nanotechnology to enhance the
microbial activity to remove hazardous pollutants from environment.
5. Types of metal used as nanobioparticles
There are vast varieties of nano particles used for nanotechnology. Some
examples are:

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6. Method used for synthesis of nanoparticles

Sourse: ResearchGate
7. Green synthesis of nano-particles: Recently researchers focus on
green synthesis of nanoparticles through microorganisms (such as
bacteria, yeasts, algae, fungi and actinomycetes) and plant extracts
(Table-1,2and3), which is very cheap (Shah et al., 2015). Antioxidant
and reducing properties of microbial enzymes and the plant
photochemical are mainly responsible for reduction of metal
compounds into their respective nanoparticles. By this process
millions of tones of nanoparticles produced worldwide. In the near
future this is expected to increase dramatically (Yadav et al., 2007,
Kumar et al. 2012, Makarov et al. 2014 and Khan et al. 2016).
8. List of plants used in nano-bioremediation (Table-1):
Nanoparticles are synthesized from number of plants as well as from
fungi and bacteria. The resul shows that plants are better candidates
for the synthesis of nanoparticles as compare to bacteria and fungi
because they require a comparatively longer incubation time for the
reduction of metal ions, while water soluble photochemical do this in
a much lesser time.

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Table 1: List of plant used for obtaining nanoparticles
Plant Nanoparticles
Citrus sinensis
Diopyros kaki (Persimmon)
Hibiscus rosa sinensis (Gurhal)
Coriandrum sativum (Dhaniya)
Emblica officinalis (Amla)
Gold and silver nanoparticles
Parthenium hysterophorus
Ocimum sp. (Tulsi)
Euphorbia hirta (Dhoodhi)
Nerium indicum (Kaner)
Pongamia pinnata
Desmodium triflorum
Opuntia ficus indica
Carica papaya
Capsicum annum
Sonchus asper
Psidium guajava
Silver nanoparticles
Terminalia catappa
Banana peel
Cinnamomum zeylanicum
Allium cepa
Azadirachta indica
Camellia sinensis
Chenopodium album
Justicia gendarussa
Mirabilis jalapa
Amaranthus spinosus
Gold nanoparticles
Brassica juncea, (Brown mustared)
Helianthus annuus
Azadirachta indica (Neem)
Nanoparticles of silver, nickel, cobalt,
zinc and copper
Diopyros kaki
Ocimum sanctum L
Platinum nanoparticles
Cinnamomum zeylanicum
Cinnamomum camphora
Gardenia jasminoides
Glycine Max. (Soybean)
Palladium nanoparticles
Jatropha curcas
Vitus vinifera
Lead Nanoparticles
Aloe vera Magnecium Nanoparticles
Source: A Review of Nanobioremediation Technologies for Environmental Cleanup:
A Novel Biological Approach, Journal of Materials and Environmental Sciences ISSN:
2028-2508(JMES, 2017, 8 (2), pp. 740-757.

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Table 2: List of bacteria used in nano-bioremediationm
Bacterium Nanoparticles
Bacillus cereus
Oscillatoria willei NTDMO1
Escherichia coli
Pseudomonis stuzeri
Bacillus subtilis
Bacillus cereus
Bacillus thuringiensis
Lactobacillus strains
Pseudomonas stutzeri
Corynebacterium
Staphylococcus aureus
Silver nanoparticles
Magnetosirillium magneticum
Sulphate reducing bacteria
Magnecium nanoparticles
Desulfovibrio desulfuricans NCIMB 8307 Palladium nanoparticles
Clostridicum thermoaceticum
Klebsiella aerogens
Escherichia coli
Cadmium nanoparticles
Rhodopseudomonas capsulate Gold nanoparticles
Alkalothermophilic actinomycete
Thermomonospora sp.
Pseudomonas aeruginosa
Lactobacillus strain
Gold nanoparticles
Sulphate reducing bacteria of the family
Desulfobacteriaceae
Zinc nanoparticles
Source: A Review of Nanobioremediation Technologies for Environmental Cleanup:
A Novel Biological Approach, Journal of Materials and Environmental Sciences ISSN:
2028-2508(JMES, 2017, 8 (2), pp. 740-757).
Table 3: List of some fungi used for nano-bioremediationm
Fungi Nanoparticles
Torilopsis species
Rhodospiridium dibovatum
Lead nanoparticles
Schizosacharomyces pombe Cadmium nanoparticles
Candida glabrata
Schizosaccharomyces pombe
Cadmium nanoparticles
Silver tolerant yeast strains MKY3
Cladosporium cladosporioides
Coriolus versicolor
Fusarium semitectum
Fusarium oxysporum
Phaenerochaete chrysosporium
Aspergillus flavus
Extremophillic yeast
Silver nanoparticles

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Aspergillus niger
Aspergillus oryzae
Fusarium solani
Trichoderma viride
Aspergillus flavus
A. furnigatus
A. terreus
A. nidulans
Silver nanoparticles
Verticillium sp.
Fusarium oxysporum
Gold and silver nanoparticle
Source: A Review of Nanobioremediation Technologies for Environmental Cleanup:
A Novel Biological Approach, Journal of Materials and Environmental Sciences ISSN:
2028-2508(JMES, 2017, 8 (2), pp. 740-757).
9. General pathway for synthesis of biogenic nanoparticles
a) Protocol for obtaining biogenic nano particles from plant extract:

Source: Link.springer.com

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b) Protocol for obtaining biogenic gold nanoparticles by fungi/bacteria.

Source: ResearchGate

50. Page | 45
c) Protocol for obtaining silver nanoparticles from algae

Source: ResearcgGate
10. Bioremediation process by nanoparticles

Fig 1: Process of bioremediation by nanoparticles

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11. List of contaminants removed by nanoparticles

12. Various applications of biogenic nanoparticles:
Nanoparticles produced by plants are gaining importance now-a-days
because of single step biosynthesis process, absence of toxicants and
occurrence of natural capping agents. The advantages of using plants for the
synthesis of nanoparticles are easily available, safe to handle and possess a
broad variability of metabolites that may aid in reduction.

52. Page | 47

Source: ResearchGate
Fig 2: Schematic representation of the key points to be addressed in future researches
on agri-nanotechnology for filling in the identified knowledge gaps

13. Conclusion
Nanoparticles produced by plants are gaining importance now-a-days
because of single step biosynthesis process, absence of toxicants and
occurrence of natural capping agents. The advantages of using plants for the
synthesis of nanoparticles are easily available, safe to handle and possess a
broad variability of metabolites. Research related to plants nanoparticles, is in
the early stages so more extensive study is needed to understand physiological,

53. Page | 48
biochemical, and molecular mechanisms of plants in relation to nanoparticles
and further work is needed to explore the mode of action of nanoparticles and
their impact on the regulation of gene expressions in plants. In the future,
adoptation of nanotechnology will extend the quality of bioremediation.
References
1. Ajitha B, Reddy YAK, Reddy PS. Green synthesis and characterization
of silver nanoparticles using Lantana camara leaf extract. Mater Sci
Eng. C. 2015;49:373-381.
2. Dauthal P, Mukhopadhyay M. Biosynthesis of palladium nanoparticles
using Delonix regia leaf extract and its catalytic activity for nitro-
aromatics hydrogenation. Ind. Eng. Chem. Res. 2013;52:18131-18139.
3. Dillewijn P Van, Caballero A, Paz JA, González-Pérez MM, Oliva JM,
Ramos JL. Bioremediation of 2,4,6-trinitrotoluene under field conditions,
Environmental Science and Technology. 2007;41(4):1378-1383.
4. Duran N, Marcato PD, Souda GIH, Valves OL. Effect of Silver
Nanoparticles Produced by Fungal Process on Textile Fabrics and Their
Effluent Treatment. Journal of Biomedical Nanotechnology.
2007;3(2):203-208. DOI: 10.1166/jbn.2007.022
5. Kalishwaralal K, Deepak V Pandian SBRK, Kottaisamy M, Kanth SBM,
Kartikeyan B, Gurunathan S. Biosynthesis of silver and gold
nanoparticles using Brevibacterium casei. Colloids Surfaces B:
Biointerfaces. 2010;77:257-262.
6. Karn B, Todd K, Martha O. Nanotechnology and in Situ Remediation: A
Review of the Benefits and Potential Risks. Environmental Health
Perspectives. 2009;117(12):1823-1831.
7. Khan MA, Khan T, Nadhman A. Applications of plant terpenoids in the
synthesis of colloidal silver nanoparticles. Adv Colloid Inter. Sci.
2016;234:132-141.
8. Kratochvil D, Volesky B. Advances in the biosorption of heavy metals,
Trends in Biotechnology. 1998;16(7):291-300.
9. Kumar KM, Mandal BK, Sinha M, Krishnakumar V. Terminalia
chebula mediated green and rapid synthesis of gold nanoparticles.
Spectrochim Acta A. 2012;86:90-494.
10. Li Y, Li B. Study on fungi-bacteria consortium bioremediation of
petroleum contaminated mangrove sediments amended with mixed
biosurfactants, Advanced Materials Research, 2011, 183-185, 1163-1167.

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11. Makarov V, Love A, Sinitsyna O, Makarova S, Yaminsky I, Taliansky
M, et al. “Green” nanotechnologies: synthesis of metal nanoparticles
using plants. Acta Nat. 2014;6:35-44.
12. Muhsin TM, Hachim AK. Mycosynthesis and characterization of silver
nanoparticles and their activity against some human pathogenic bacteria.
World J Microbiol. Biotechnol. 2014;30:2081-2090.
13. Pandey IP, Ahmed SF, Chhimwal S, Pandey S. Chemical composition
and wound healing activity of volatile oil of leaves of Azadirachta
indica A. juss. Adv Pure Appl. Chem. 2012;1:2167-0854.
14. Prokop G, Schamann M, Edelgaard I. Management of Contaminated Sites
in Western Europe, European Environment Agency, Copenhagen,
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15. Rizwan MD, Singh M, Mitra CK, Morve RK. Ecofriendly Application of
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16. Sánchez Antoni, Sonia Recillas, Xavier Font, Eudald Casals, Edgar
González, Víctor Puntes. Ecotoxicity of, and remediation with,
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17. Shah M, Fawcett D, Sharma S, Tripathy SK, Poinern GEJ. Green
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Wiley-Blackwell, Oxford, 2010, 40.
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Oxford University Press, Washington, DC, 2005, 248-261.

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Chapter - 4
Fluoride in Water-Cause, Health Risk and
Removal Studies



Authors
Dr. Meena Chakraborty
Govt. Naveen College Bori, Durg, Chhattisgarh, India
Dr. Manisha Thakur
Govt. Naveen College Bori, Durg, Chhattisgarh, India

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58. Page | 53

Chapter - 4
Fluoride in Water-Cause, Health Risk and Removal Studies
Dr. Meena Chakraborty and Dr. Manisha Thakur


Abstract
Appropriate health is the basic need of human life. Large numbers of
elements are available around us to protect us from illness and to provide
good health to us. Fluoride is an element with distinctive properties as small
amount of fluoride is good for dental health to prevent cavities but as the
concentration of fluoride increases in body, it shows adverse effect on
human health in terms of dental and skeletal fluorosis. Drinking water is the
major source of fluoride intake by human beings. Therefor this study will
focus on cause of fluoride in water, factors affecting concentration of
fluoride in water, different methods available for determination of fluoride
and methods of removal of fluoride from water.
Keywords: Fluoride, dental health, dental and skeletal fluorosis
1. Introduction
Pure drinking water is the basic need of our life, but in present scenario
more than one billion people all over the world have no access to safe
drinking water. Rapid industrialization, deforestation and damage of
environment on behalf of development are responsible for this. Dissolution
of inorganic and organic pollutants from geogenic origin as well as from
anthropogenic activities degrades the water quality up to the extreme level.
Fluoride is one of them. Fluoride the negatively charged ion is one of the
most abundant element found on earth. Fluoride and hydroxide ion easily
replaces each other from minerals as they have same charge and have almost
same size (Hem, 1985). Therefore, it forms several minerals with cations.
Fluoride is an important constituent of many minerals such as fluorspar, rock
phosphate, cryolite, mica, hornblende, apatite, fluorite and topaz
(Chakraborty et al., 2021). These minerals are part of rocks and when
ground water comes in contact with rocks, these minerals dissolved in water
and contaminate the ground water with fluoride (Handa 1975; Farooqi et al.
2007; Singh & Garg 2012). Not only nature, human activities such as

59. Page | 54
discharge of industrial waste water, agriculture run off, sewage leakages,
mining, house hold chemicals are also responsible for contamination of
water bodied with fluoride (Owa, 2014). Apart from water fluoride is present
in many food items such as tea, coffee, juice, sodas, raisins etc. (IMSC,
1997). Therefore, fluoride enters in food chain through drinking water and
food items. Small concentration of fluoride (up to 0.5 mg/L) is good for
dental health as it prevents dental cavities, but as concentration of fluoride
becomes higher (more than 1.5 mg/L) it causes severe health issues such as
dental fluorosis, skeletal fluorosis, rachitis, neurological disorders, tendon
and ligament ossification, disorders of kidneys, thyroid, liver and testicles
(Dong & Wang, 2016; Canciam, C.A. & Pereira, 2019). In some countries,
fluoride is added to drinking water for good dental health (Reeves, 1986,
1994), but if concentration of fluoride in drinking water is not regulated by
authorities then it can cause adverse health effects. Fluorosis has become
major threat in many countries such as China, India, Pakistan, West Africa,
Thailand, China, Sri Lanka, and Southern Africa. India is also seriously
affected by fluorosis (Fawell, 2006). The Indian states like Andhra Pradesh,
Punjab, Haryana, Rajasthan, Gujarat, Tamil Nadu and Uttar Pradesh are
suffering by problem of fluorosis extremely (Kumaran, et al., 1971; Teotia et
al., 1984). Dissolution of fluorite, apatite and topaz from the local bedrock is
the main source of high concentration of fluoride in ground water in affected
areas (Fawell, 2006). Rural population of these states are affected the most
because ground water is the only source of drinking water for them. The safe
limit of fluoride intake in different countries is different because
concentration of fluoride in water depends on geological structure of the
area, climate pH and chemical constitution of water bodies. Therefore, to
prevent fluorosis, it is essential to monitor as well as to remove excess
concentration of fluoride in drinking water as drinking water is the main
source of fluoride intake by human beings. This chapter will focus on source
of fluoride, factors affecting fluoride concentration in ground water, health
effects and removal methods of fluoride from water.
2. Sources of fluoride
Fluoride enters in food chain through water and food items mainly
which are listed as below:
Fluoridated water
Fluoride protects teeth against cavities; therefore, some countries add
fluoride to drinking water in the form of sodium fluoride (NaF), fluorosilicic
acid (H2SiF6) or sodium fluorosilicate (Na2SiF6) (CDCP 2010, McDonagh et

60. Page | 55
al., 2000). Fluoridated water has no specific smell, taste or appearance. In
case of ground water, when it comes in contact with fluoride minerals
bearing rocks, fluoride gets dissolved in it.
Food
Many food items contain fluoride in them, but their consumption is less
in our every day’s life. But some food items are very high in fluoride as
listed below I Table 1 and shown in figure 1:
Table 1: Food items with high fluoride concentration
S. No. Food items
Fluoride
concentration in ppm
References
1. Black tea (per cup) 3-5 Kanduti et al., 2016
2. Green tea (per cup) 1.2 Kanduti et al., 2016
3. Shellfish products 2-3 Kanduti et al., 2016
4. Wine 1-2 Kanduti et al., 2016
5. Fluoridated salt (5 g) 1 Linus Pauling Institute
6. Fluoridated milk (200 mL) 0.5-1 Linus Pauling Institute
7. Chicken (3 oz, 85 g) 0.05-0.9 Linus Pauling Institute
8. Grape juice (1 cup, 237 mL) 0.05-0.7 Linus Pauling Institute


Fig 1: Food with high fluoride content
(Source: nutrientsreview.com)
Fluoridated toothpaste
Fluoridated toothpastes contain either sodium fluoride or mono-
fluorophosphate. They are helpful to reduce the damage of tooth enamel
caused by bacteria. Some doctors believe that these toothpaste are helpful to
reduce dental cavity in the children of age group 3-6 (Wright et al.,
2014). Fluoride helps to prevent acid attacks on tooth enamel and also repair
tooth decay in early stages.

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Fig 2: Benefit of fluoride toothpaste on dental health
(Source: https://www.verywellhealth.com/facts-about-fluoride-toothpaste-4587999)
Fluoride mouthwash
Mouthwash is used to control bad breath and sodium fluoride is used as
antibacterial agent in mouthwash. Fluoride in mouthwash strengthens the
tooth enamel and helps to reduce cavities (Asl Aminabadi et al., 2007).
Oral fluoride supplements
Fluoride supplements are generally have sodium fluoride or mono-
fluorophosphate in them. These supplements are prescribed to the children of
age group 6 months to 16 years who live in the areas with a low
concentration of fluoride in the drinking water. So, they are at high risk of
developing dental caries, but these supplements should not give to the
children who drink fluoridated water because they may develop dental
fluorosis (Rozier et al., 2010). Requirement of fluoride supplements for
children recommended by American Dental Association is shown in Table 2.
Table 2: Fluoride Supplement Schedule as recommended by American Dental
Association
Age
If Fluoride level in
drinking water is
less than 0.3 ppm
If Fluoride level in
drinking water is
within 0.3-0.6 ppm
If Fluoride level in
drinking water is
more than 0.6 ppm
Birth to 6 months None None None
6 months to 3 years 0.25 mg/day None None
3 years to 6 years 0.50 mg/day 0.25 mg/day None

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6 years to 16 years 1.0 mg/day 0.50 mg/day None
Source: Linus Pauling Institute
But out of all these sources, drinking water is the main source of
fluoride intake by human beings. Ground water and surface water is used for
drinking purpose, but ground water is the major source of drinking water in
most of the countries in the world. Therefore, fluoride contaminated ground
water is the important source of fluoride intake for us.
3. Factors affecting fluoride concentration in ground water
Geology
During weathering and circulation of water in rocks and soils, fluorine
can be leached out and dissolved in groundwater and thermal gases. The
fluoride content of groundwater varies greatly depending on the geological
settings and type of rocks. The most common fluorine-bearing minerals are
fluorite, apatite and micas. Therefore fluoride problems tend to occur in
places where these minerals are most abundant in the host rocks (Sharma et
al., 2011).
Contact time
 The ultimate concentration of fluoride in groundwater largely
depends on reaction times with aquifer minerals. High fluoride
concentrations can be built up in groundwaters which have long
residence times in the aquifers. Such groundwaters are usually
associated with deep aquifer systems and a slow groundwater
movement.
 Shallow aquifers which contain recently infiltrated rainwater
usually have low fluoride. Exceptions can occur in shallow aquifers
situated in active volcanic areas affected by hydrothermal alteration.
Under such conditions, the solubility of fluorite increases with
increasing temperature and fluoride may be added by dissoluition of
HF gas (Hudak and Sanmanee, 2003).
Climate
 Arid regions are prone to high fluoride concentrations. Here,
groundwater flow is slow and the reaction times with rocks are
therefore long. The fluoride contents of water may increase during
evaporation if solution remains in equilibrium with calcite and
alkalinity is greater than hardness. Dissolution of evaporative salts
deposited in arid zone may be an important source of fluoride.

63. Page | 58
 Fluoride increase is less pronounced in humid tropics because of
high rainfall inputs and their diluting effect on the groundwater
chemical composition (Brunt et al., 2004).
Chemical composition of groundwater
 High-fluoride groundwaters are mainly associated with a sodium-
bicarbonate water type and relatively low calcium and magnesium
concentrations. Such water types usually have high pH values.
 Information on chemical composition of groundwater can be used
as an (proxy) indicator of potential fluoride problems (Handa,
1975).
4. Effect of Fluoride on human health
Fluoride functions in the human body
Bacterias produces acid in mouth and decreases the pH of saliva. In this
acidic environment demineralization of enamel begins and cavities are
formed. Fluoride in tooth enamel replaces hydroxyl ion and converts
hydroxyapatite into fluorapatite. Fluorapatite thus formed is more resistant to
the acids produced by bacteria inside the mouth. This process is known as
remineralisation. Due to repeated cycles of demineralization and
remineralisations too the enamel become strong (Buzalaf et al., 2011)
Dental Fluorosis: Causes, Symptoms
Long term consumption of fluoride can cause change in dental enamel
which is known as dental fluorosis. Dental fluorosis is a condition that
causes changes in the appearance of tooth enamel. It occurs when children
regularly consume fluoride during the teeth-forming years that is up to age of
8 years. Dental fluorosis results in white or brown speckles on your teeth as
per its severity (Figure 3).

Fig 3: Mild and Severe dental fluorosis
(Source: Wikipedia, CC licence)

64. Page | 59
Skeletal fluorosis
Skeletal fluorosis refers to accumulation of fluoride in bone which
results in bone hardening (osteosclerosis). It occurs due to chronic exposure
to fluoride-contaminated groundwater over a long period of time. It has
various stages which are shown below in the Table 3.
Stages of skeletal
fluorosis
Symptoms References
Stage 1 Skeletal
fluorosis
Osteosclerosis, sporadic pain and joint stiffness
Jolly, 1968
Stage 2 Skeletal
fluorosis
Chronic joint pain, arthritic symptoms, slight
calcification of ligaments and muscle tendons
Stage 3 Crippling
skeletal fluorosis
Limitation of joint movement, calcification of
ligaments, neck and vertebral column, crippling
deformities of spine and major joints, muscle wasting,
neurological defects or compression of spinal cord
Thus consumption of fluoride contaminated drinking water can cause different effects
on health which is mentioned in Table 4:
Table 4: Health effects of fluoride contaminated drinking water
Fluoride level (mg/L) Effect on health Reference
<0.5 Dental cavities
Dissanayake, 1991; Edmunds
and Smedley, 1996;
Ravindhranath et al., 2015
0.5-1.5 Ideal dental health
1.5-4.0 Dental fluorosis
4.0–10 Dental and skeletal fluorosis
>10.0 Crippling fluorosis

5. Methods for determination of fluoride
Different methods are available for determination of fluoride
concentration in water such as potentiometry, colorimetry, chromatography,
optical method etc. But every method has its own advantages and
disadvantages, which are compared in Table 5.
Table 5: Comparison of fluoride determination methods
Method Advantage Disadvantage Reference
Optical method
Sensitive and fast
analysis, small volume
of sample required
Complex
instrumentation
Sahu et al., 2016;
Xiong et al., 2017
Ion
chromatography
Easy to operate Costly, time consuming Hakim et al., 2010
Potentiometry
High accuracy and
sensitivity
Influenced by the
presence of co-ions and
temperature
Sahu et al., 2016

65. Page | 60
Colorimetric
method
Simple to operate, low
cost
Influenced by
interference of ions,
requires special
treatment of samples
Sahu et al., 2016

6. Fluoride removal methods
Because of the adverse health effects of fluoride, removal of fluoride
from water is must to provide safe drinking water to the population.
Different methods are there for removal of fluoride from water, but every
method has its own pros and cons which are compared in Table 6.
Table 6: Comparative study of methods for removal of fluoride from water
Fluoride Removal
Method
Pros Cons Reference
Adsorptive materials:
Effective, easy to
use, less Costly,
availability of
various adsorbents
pH sensitive,
efficiency affected
by co-ions present
in water
Bhatnagar et al.,
2011
Filtration through
Membrane:
Effective; also
remove
contaminates other
than fluoride
Costly, production
of toxic waste
water
Chakrabortty et
al., 2013;
Meenakshi and
Maheshwari,
2006
Coagulation/precipitation:
Effective; includes
easily available
chemicals
Costly, pH
sensitive,
efficiency affected
by co-ions present
in water,
formation of toxic
sludge
El-Gohary et al.,
2010;
Meenakshi and
Maheshwari,
2006
Ion-exchange: Effective
Costly, pH
sensitive,
efficiency affected
by co-ions present
in water, toxic
solid waste
produced
Meenakshi and
Maheshwari,
2006
Electrochemical
treatments:
Effective; highly
selective
Costly
Piddennavar,
2013; Tomar
and Kumar,
2013

7. Conclusion
Fluoride is a natural element which is available around us. Sources of
fluoride intake in human body are respiration, dietary intake, fluoride
supplements and through fluoride contaminated drinking water. Out of these,

66. Page | 61
drinking water is the main source of fluoride for human beings. Drinking
water gets contaminated with fluoride due to dissolution of fluoride minerals
from rocks as well as due to anthropogenic activities. Small amount of
fluoride is advantageous for dental health but long-term exposure of elevated
concentration of fluoride causes health problems as dental and skeletal
fluorosis. Therefore, it becomes very important to determine amount of
fluoride in drinking water, identify the source of excessive fluoride in water
and removal of excess of fluoride from water to provide good health to the
population of a country.
References
1. Asl Aminabadi N, Balaei E, Pouralibaba F. The Effect of 0.2% Sodium
Fluoride Mouthwash in Prevention of Dental Caries According to the
DMFT Index. J Dent Res Dent Clin Dent Prospects. 2007;1(2):71-6.
Doi: 10.5681/joddd.2007.012. Epub 2007 Sep 10. PMID: 23277837;
PMCID: PMC3525928.
2. Bhatnagar A, Kumar E, Sillanpaa M. Fluoride removal from water by
adsorption-A review. Chem. Eng. J. 2011;171:811-840.
3. Brunt R, Vasak L, Griffioen J. Fluoride in Groundwater: Probability of
Occurrence of Excessive Concentration on Global Scale. Report SP
2004-2. International Groundwater Resources Assessment Centre
(IGRAC), 2004.
4. Buzalaf MA, Pessan JP, Honório HM, Ten Cate JM. Mechanisms of
action of fluoride for caries control. Monogr Oral Sci. 2011;22:97-114.
Doi: 10.1159/000325151.
5. Canciam CA, Pereira NC. Assessment of the Use of Epicarp and
Mesocarp of Green Coconut for Removal of Fluoride Ions in Aqueous
Solution. Int. J Chem. Eng., 2019, 8.
6. Centers for Disease Control and Prevention (August 2010). 2008 Water
Fluoridation Statistics. Retrieved August 10, 2011.
7. Chakrabortty S, Roy M, Pal P. Removal of fluoride from contaminated
groundwater by cross flow nanofiltration: Transport modeling and
economic evaluation. Desalination. 2013;313:115-124.
8. Chakraborty M, Pandey M, Pandey P. Fixed bed column performance of
Tinospora cordifolia for defluoridation of water. Water Supply.
2021;21(5):2324-2332.

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9. Dissanayake CB. The fluoride problem in the groundwater of Sri Lanka-
environmental management and health. Int. J Environ. Stud.
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10. Dong S, Wang Y. Characterization and adsorption properties of a
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removal. Water Res. 2016;88:852-860.
11. El-Gohary F, Tawfik A, Mahmoud U. Comparative study between
chemical coagulation/precipitation C/P versus coagulation/dissolved air
flotation D/DAF for pre-treatment of personal care products PCPs
wastewater. Desalination. 2010;252:106-112.
12. Owa FW. Water pollution: sources, effects, control and managements.
International Letters of Natural Sciences. 2014;3:1-6.
13. Farooqi A, Masuda H, Kusakabe M, Naseem M, Firdous N. Distribution
of highly arsenic and fluoride contaminated groundwater from east
Punjab, Pakistan, and the controlling role of anthropogenic pollutants in
the natural hydrological cycle. Geochemical Journal. 2007;41:213-234.
14. Fawell J, Bailey K, Chilton J, Dahi E, Magara Y. Fluoride in drinking-
water. IWA publishing, 2006.
15. Hakim M, Waqar F, Jan S, Muhammad B, Khan SA. Comparison of Ion
Chromatography with Ion Selective Electrodes for the Determination of
Inorganic Anions in Drinking Water Samples. Pakistan Journal of
Scientific and Industrial Research. 2010;53(1):6-13.
16. Handa BK. Geochemistry and genesis of fluoride-containing ground
waters in India. Groundwater. 1975;13(3):275-281.
17. Hem JD. Study and Interpretation of the Chemical Characteristics of
Natural Water. Water Supply Paper 2254, 3rd edition, US Geological
Survey, Washington, D.C., 1989, 263.2
18. Hudak PF, Sanmanee S. Spatial Patterns of Nitrate, Chloride, Sulfate
and Fluoride Concentrations in the Woodbine Aquifer of North-Central
Texas. Environmental Monitoring and Assessment. 2003;82:311-320.
19. Institute of Medicine (US) Standing Committee on the Scientific
Evaluation of Dietary Reference Intakes. Dietary reference intakes for
calcium, phosphorus, magnesium, vitamin D, and fluoride, 1997.
20. Jolly SS. An Epidemiological. Clinical and Biochemical Study of
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21. Kanduti Domen, Sterbenk Petra, Artnik Barbara, Fluoride: A review of
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23. McDonagh MS, Whiting PF, Wilson PM, Sutton AJ, Chestnutt I,
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24. Meenakshi RC, Maheshwari J. Fluoride in drinking water and its
removal. J Hazard. Mater. 2006;137:456-463.
25. Piddennavar R. Review on defloridation techniques of water. Int. J Eng.
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26. Reeves TG. Water Fluoridation. A Manual for Engineers and
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27. Reeves TG. Water Fluoridation. A Manual for Water Plant Operators.
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28. Rozier RG, Adair S, Graham F, et al. Evidence-based clinical
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29. Sahu N, Thakur R, Bansod BK. Detection of Fluoride Ion in Water: An
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30. Sharma BS, Agrawal Jyoti, Gupta Anil K. Emerging Challenge:
Fluoride Contamination in Groundwater in Agra District, Uttar Pradesh.
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33. Tomar V, Kumar D. A critical study on efficiency of different materials
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34. Wright JT, Hanson N, Ristic H, Whall CW, Estrich CG, Zentz RR.
Fluoride toothpaste efficacy and safety in children younger than 6 years:
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35. Xiong Y, Wu J, Wang Q, Xu J, Fang S, Chen J, et al. Optical sensor for
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interaction and fiber-optic integration. Talanta. 2017;174:372-379.

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Chapter - 5
Status of Coral Reefs, their Ecological Value and
Conservation Management



Authors
Ranjeet Singh
Department of Aquaculture, College of Fisheries, G.B. Pant
University of Agriculture and Technology, Pantnagar, Udham
Singh Nagar, Uttarakhand, India
Anurag Semwal
Department of Aquaculture, College of Fisheries, G.B. Pant
University of Agriculture and Technology, Pantnagar, Udham
Singh Nagar, Uttarakhand, India
Neelesh Kumar
Department of Aquaculture, College of Fisheries, G.B. Pant
University of Agriculture and Technology, Pantnagar, Udham
Singh Nagar, Uttarakhand, India

71. Page | 66

72. Page | 67

Chapter - 5
Status of Coral Reefs, their Ecological Value and
Conservation Management
Ranjeet Singh, Anurag Semwal and Neelesh Kumar


Abstract
Ocean acidification and global warming will endanger coral bleaching
more and more under conditions predicted for the twenty-first century. Despite
having enormous ecological, economic and aesthetic benefits, around 20% of
the world's coral reefs are said to have been demolished. Around 500 million
people all around the world, generally in developing countries, depends
directly on coral reefs, which have the maximum biodiversity of any
ecosystem on the planet earth. At the local level, water pollution, coastal
development and overfishing are damaging coral reefs, while carbon pollution
continues to be the biggest threat to reefs worldwide. The most biodiverse
ecosystems on earth are supported by coral reefs. Coral bleaching has an
influence on people's safety, livelihoods, and access to food. Fish populations
that rely on reefs and other kinds of marine life can decline dramatically in the
absence of living food supplies and habitat. Corals interrupt the natural cycle
of other species, making it more difficult for them to obtain food, escape
threats, and have a place to rest and reproduce. Coral reefs all across the world
will face a dreadful destiny in the coming decades in our lifetimes if we
continue to pollute the ocean at such a high rate. Although the loss of all coral
due to bleaching is not fatal, we must take action right away if we wish to
preserve coral for future generations.
Keywords: Coral reefs, acidification, biodiverse, bleaching
Introduction
Coral reefs play a crucial role in the ecosystem services and goods that
marine tropical and subtropical nations receive from them. Around 500
million people all around the world, mostly in developing nations, directly
depend on coral reefs, which have the uppermost biodiversity of any
ecosystem on the planet earth. Basically, corals are animals, despite the
circumstance that they can look like plants and are frequently mistaken for

73. Page | 68
rocks. Corals are classified under phylum Cnidaria and class Anthozoa in
science. They are among the severely endangered ecosystems on Earth, due to
dramatic climatic changes and global warming, as well as increasing local
pressures. Over the previous 100 years, ocean temperatures in many tropical
locations have risen by over 1 °C and they are continuously rising at 1-2 °C
per century. Coral’s bleaching happens when the temperature tolerance of
corals and the zooxanthellae that live inside them is surpassed. Significant live
coral losses have been caused by mass bleaching in several parts of the planet.
Significant threats exist to coral reefs. They are susceptible to the effects of
human activity because they are found in coastal areas and there aren't many
unspoiled reefs left (Bellwood et al., 2004; Graham et al., 2014). By the end
of this century, all 29 reef-containing World Heritage sites would no longer
have their coral reef ecosystems, if greenhouse gas emissions keep increasing
at the current rate according to UNESCO. The sole chance for coral reef
survival on a worldwide basis is provided by the Paris Agreement's target of
keeping the average global temperature far below 2 °C over pre-industrial
levels. Despite the fact that the oceans have absorbed a third of all emissions,
the volume of carbon dioxide (CO2) in the atmosphere has elevated during the
industrial revolution from 280 to 405 ppm.
Categories of coral
Corals are two-layered, communal invertebrates related to jellyfish and
sea anemones. Polyps, which are little individuals, make up corals.
Types of corals:
1) Soft Corals
2) Stony Corals
1) Soft corals: The term "soft coral" refers to an organism without a
calcium carbonate skeleton. The majority of the world's soft corals
are located in tropical or subtropical environments. Soft corals can
move and flow with the currents of the water because to their flexible
bodies. Spicules, which are microscopic pieces of calcium that have
been solidified, are present throughout their bodies and offer support
(NOAA).
2) Stony (hard) corals: The base of coral reefs are hard coral species.
One-celled organisms called zooxanthellae provide sustenance for
some stony corals. Coral polyps receive 95% of the food produced
by zooxanthellae, which are single-celled organisms that use sunlight
for photosynthesis. This relationship benefits the coral as well as the
zooxanthellae.

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Coral reefs
Coral reefs are home to one of the most diverse environments on earth.
Although it might be more accurate to refer to rainforests as the coral reefs of
the land, coral reefs are commonly referred to as the rainforests of the sea. The
invertebrate species known as coral polyps, which play a significant role in
the formation of reefs, can take many different forms, including huge colonies
that form entire reefs, gracefully flowing fans, and even minuscule solitary
organisms. Corals come in a variety of types, some of which live in warm,
shallow tropical seas and others of which are found in the chilly, dark depths
of the ocean. Corals grow very slowly; some barely increase by 3-20 mm
annually. Hence, some reefs develop over millions of years (Veron, 2002).
These corals leave behind their calcium carbonate skeletons as they develop
and perish. Other corals grow on these skeletons. Coral walls, which are
enormous rock walls, start to form as the years go by. These walls develop
crevices, ledges, and tunnels as the waves and currents strike these reefs. There
are various kinds of coral reefs. Fringing reefs, barrier reefs, and atolls are the
three primary types of reefs (Veron, 2002).
1) Barrier Reefs: A barrier reef is found where the main coast meets a
deep waterway or lagoon. Early formation takes place in the open
ocean off the coast and it continues to grow parallel to or in the
direction of the coastline. Barrier reefs with shallow lagoons can
occasionally resemble fringing reefs, but they differ from them
because of where they came from and because they typically have
deeper lagoons (Elias and Alderton, 2020). Sometimes they can be
located miles from the coast (10-100 km). Barrier reefs can develop
in rather deep water because the current coral frequently develops
over the remains of corals that once existed in the same region during
the last ice age, when sea level was lower.
2) Fringing Reefs: One of the most prevalent types of reefs is a fringe
reef, which is made up of shallow reef platforms that attach to the
adjacent shore and range in width from 10 to 100 metres. These
platforms tend to face parallel to the coast and spread outward. In the
entire offshore Bioregion, fringed reefs can be found along the
seaward edges of offshore islands. Coral reefs that form in shallow
waters are known as fringe reefs. They are either immediately along
the coast or just across a small body of water from it. There are
numerous fringing reefs surrounding Thailand and Sri Lanka.

75. Page | 70
3) Atolls: Atolls are essentially annular reef and reef-island systems that
are primarily found in oceanic mid-plate environments. They are
perched above undersea volcanic peaks (Sivaperuman et al., 2018).
Atolls develop around an island, which sinks in relation to the sea
level as a result of ceasing volcanic activity or being swamped as sea
levels rose during the previous ice age. A centre lagoon is surrounded
by atolls. There are 26 atolls total in the Maldives.
What's the problem?
Human activity has a big impact on coral reefs. Coral reefs are
deteriorating on a global scale. Destructive practises include coral mining,
organic and inorganic pollution, overfishing, blast fishing, digging canals, and
access to islands and bays. From preindustrial times, anthropogenic
greenhouse gaseous emission has elevated the earth's surface temperature by
about 1 °C. Corals expel the symbiotic algae living in their tissues, which are
responsible for their colour, when conditions, like temperature changes. Coral
reefs are currently one of the planet's most endangered ecosystems due to the
unprecedented mass coral bleaching phenomenon that came from this and
rising local pressures. When ocean temps rise by 1-2 °C over several weeks,
bleaching, which turns corals white, can happen. If corals are bleached for a
long time, they ultimately die. Large numbers of corals frequently perish as a
consequence of coral bleaching events. For last few years running, mass
bleaching episodes have affected reefs all around the world. The Great Barrier
Reef in Australia and the North-western Hawaiian Islands in the United States
are both well-known corals that have experienced the worst bleaching in
recorded history with disastrous effects. For example, the Great Barrier Reef's
corals were devastated by bleaching in 2016 and 2017, which killed almost
50% of them. Corals are unable to withstand the current frequency of global
temperature rise-induced bleaching episodes. As temperatures increase,
bleaching incidents will worsen and happen more frequently. Even
occurrences that occur twice every ten years, according to scientists, can
threaten coral survival. According to the first global scientific assessment of
the effects of climate change on World Heritage coral reefs, published in 2017
by UNESCO, all 29 reef-containing World Heritage sites' coral reefs would
cease to exist as functional coral reef ecosystems by the end of this century if
humans continue to release greenhouse gases.
Coral Reefs: Environmental and Economic Importance
Coral reefs hold the most biodiversity of any ecosystem globally. Despite
covering less than 0.1% of the ocean bottom, reefs are home to many other

76. Page | 71
marine animals and more than one-quarter of all marine fish species.
Additionally, reefs provide a variety of ecosystem benefits, such as the upkeep
of the fishing and tourism sectors, protection from flooding, and food for
subsistence. The most beautiful and varied marine ecosystems on the planet
are coral reefs. Coral reefs are productive and complex ecosystems that are
home to tens of thousands of species, many of which have no known scientific
names. They are well-known for their attractiveness, biological variety,
attractiveness, and great productivity Charles Darwin and other early scientists
were puzzled by the peculiar placement of these extraordinarily fruitful
ecosystems in oceans that are incredibly deficient in the nutrients required for
primary production. Therefore, their disappearance will have an impact on the
economy, society, and health. According to estimates, almost 500 million
people worldwide, particularly in developing countries, directly depend on
coral reefs for their daily needs. According to a 2014 analysis that was
published in the journal Global Environmental Change, coral reefs are worth
$1 trillion in terms of their social, cultural, and economic contributions. A
2015 report by WWF estimated that by 2100, the loss of reef ecosystem
services resulting from climate change will cost at least US$500 billion
annually. A critical measure of the health of the world's ecosystems are coral
reefs. They serve as a warning system for what can happen to other, less
sensitive systems, such river deltas, if climate change is not rapidly addressed.
As coral reef survival reaches its breaking point, other ecological systems may
experience a more rapid and irreversible decline.
Ocean acidification and global warming will hinder carbonate accretion
in the 21st century, with coral bleaching becoming more common and ocean
acidification rare on reef systems. As a result, carbonate reef structures won't
be preserved and coral ecosystems would be less diversified. Furthermore,
climatic change intensifies local stresses brought on by declining water quality
and overfishing of essential species, bringing reefs closer and closer to the
point of functional collapse. Coral reefs are incredibly productive ecosystems
that offer a wide range of services to people.
 Furnishing services: Coral reefs plays a important role in the
economy and in sustaining human life. Over 500 million people rely
on coral reefs both directly and indirectly for their food, livelihoods,
and other resources (Wilkinson, 2004).
 Assistance services: Coral reefs have a significant role in the
accretion of land. Primary productivity on coral reefs is quite high,
averaging 5-10g C/m
2
/day. Coral reefs have a huge variety (Sorokin,
1995).

77. Page | 72
 Governing services: Coral reefs shield the coastline from flooding
and decrease erosion.
 Ethnic services: Coral reefs offer recreational, aesthetic, and
inherently valuable benefits.
The Indo-Malayan triangle, which includes Indonesia, Malaysia, the
Philippines, and Papua New Guinea, is home to most of the world's coral
species, making Southeast Asia the region with the most coral variety. Almost
600 of the world's 800 species of coral that produce reefs are found in this
area, which has 100,000 km
2
of coral reefs (34% of the world's total) (Tun,
2004; Burke et al., 2002).
Changing ecological dynamics: Coral predators and competitors
Pathogens are not the only serve as biological enemies of corals;
significant mortality is also linked to competition overgrowth and predator
feeding. Evidence that these causes of death have increased in recent decades
is mounting, indicating that corals have been fighting a losing struggle on this
front as well.
Seaweeds are currently corals main competitors on most reefs. There is
widespread agreement that the amount of herbivory and the availability of
nutrients have a significant impact on the competitive balance between corals
and macroalgae, but there is ongoing discussion over their relative importance
and their interactions. Yet, small-scale investigations suggest that herbivory is
frequently likely to be a considerably bigger factor in restricting algal
development than nutrients. The history of Kaneohe Bay in Hawaii and
Discovery Bay in Jamaica provide a more comprehensive look at many of the
pertinent issues. When sewage from Kaneohe Bay was diverted starting in
1977 due to worries about eutrophication brought on by the growth of the
green bubble alga Dictyosphaeria cavernosa, it provided a chance to see how
the reef ecosystem responded to this significant, if uncontrolled, experiment.
Little transitory algae immediately colonised dead substrates in Discovery
Bay, but over time, larger, long-lived species that could outgrow living coral
took their place. Algal cover went from 4% to 92% as a result, whereas coral
cover went from 52% to 3%. Several places have had changes of a similar
nature, albeit somewhat different in timing and scope. According to the
widespread view, the main reason for the change from a coral-dominated to
an algal-dominated reef was the death off of such a significant herbivore,
especially in light of the low abundance of herbivorous fishes owing to
overfishing. Eutrophication and overfishing, two anthropogenic conditions
that can harm coral competitors, have also been linked to some of the dramatic

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increases of coral predators (corallivores) that have been observed over the
past few decades. The most notorious of them is the crown-of-thorns starfish,
Acanthaster planci, but there have also been reports of predatory snail
explosions, especially in the genus Drupella.
The scale of outbreaks appears to be unprecedented because the size
structure of corals prior to the earliest known outbreaks could not have existed
if the current magnitudes and frequencies of outbreaks were a long-term
feature of reefs, at least in the case of Acanthaster. Yet, not all research agree
that the former is significant or that the latter is not. Even little is known about
the causes of Drupella outbreaks (Knowlton, 2001).
Major Pressures to Coral Reefs
In neighbouring shallow water, the bulk of coral reefs can be found. As a
result, they are particularly vulnerable to the detrimental effects of human
activity, both directly through the exploitation of reef resources and indirectly
through the effects of surrounding human activities on land and in the coastal
zone. Several human activities that affect coral reefs are intimately intertwined
into the social, cultural, and economic fabric of the nearby coastal towns.
Coral reefs are frequently threatened by regional factors, such as:
 Damage or destruction to the physical environment brought on by
excessive recreational use, coastal development, dredging,
quarrying, destructive fishing techniques and equipment, boat
anchors and groundings (touching or removing corals) etc.
 Pollutants from the land that gets into the oceans along the shore.
Pollution from land-based activities can take many different forms
and comes from a wide range of sources, including:
 Forests, farms, urban stormwater runoff, and coastal development all
contribute to sedimentation.
 Sedimentation has been identified as the primary stressor for the
survival and recovery of coral species and their ecosystems.
Sediment near the reef can smother corals and make it difficult for
them to grow, reproduce and mate.
 Nutrients (nitrogen and phosphorous) majorly from animal manure,
sewage discharges (including from wastewater treatment facilities
and septic systems), and home and commercial fertiliser use.
 Although it is generally believed that nutrients are beneficial for
marine ecosystems, coral reefs are adapted to low nutrient levels; as

79. Page | 74
a result, an excess of nutrients can result in the growth of algae, which
blocks sunlight and depletes the oxygen corals need to breathe.
Frequently, this results in an imbalance that affects the entire
ecosystem. Moreover, a surplus of nutrients may encourage the
development of coral-harming bacteria and fungi.
 Pathogens from poorly treated sewage, rainfall, and livestock waste
runoff.
 Although uncommon, germs and parasites from faecal contamination
can harm corals, particularly if they are already under stress from
other environmental factors. Coral disease does occur in ecosystems
that are healthy, but the introduction of pollution that contains
pathogens can elevate the occurrence and severity of disease
outbreaks.
 Hazardous elements like as metals, organic compounds and
pesticides, which are present in industrial runoff waste, sunscreens,
urban and agricultural runoff waste, mining operations, and landfill
runoff.
 Pesticides may affect the development, reproduction, and other
physiological processes of coral. Herbicides, in particular, can
destroy the symbiotic algae (plants). This can damage their
connection to the coral and result in bleaching. Only a few of the
chemical substances and metals that are believed to affect coral
reproduction, growth rate, feeding and defensive responses are
polychlorobiphenyls (PCBs), oxybenzone and dioxin.
 Stormwater runoff, microplastics, and garbage from incorrect
disposal.
 Marine debris can entangle and kill reef species as well as break or
harm corals. It includes waste like plastic bags, bottles, and
abandoned fishing gear. Moreover, it can hook on corals and stop
sunlight, which is necessary for photosynthesis. Degraded plastics
and microplastics (like soap beads) could hinder coral digestion and
introduce harmful chemicals if coral, fish, sea turtles, and other reef
animals ingest them.
 By, for instance, reducing the population of grazing fish that keep
corals free of algal overgrowth, overfishing can change the structure
of the food chain and cause a cascade effect. Moreover, the practise
of "blast fishing", which includes using explosives to kill fish, can
injure corals physically.

80. Page | 75
 The removal of coral for the aquarium trade, jewellery, and oddities
may lead to overharvesting of particular species, the destruction of
the habitat for the reefs and a decrease in biodiversity.
The cumulative effects of these stressors may reduce the reef's overall
resilience and increase its susceptibility to illness and invasive species.
Invasive species may cause the biological checks and balances of a reef
ecosystem to fall out of balance.
Present state of the world's coral reefs
On the condition of coral reefs, there is regrettably no easy solution. The
level of damage to coral reefs around the world varies, and some have made a
full recovery. Overfishing, pollution, and climate change are likely to blame
for the degradation of about half of the world's reefs. In some areas, the
amount of hard coral has drastically decreased, and there has been a noticeable
shift in the organisation of the coral community, including a loss of diverse
and vulnerably coral species. The average global hard coral cover was high
and constant between 1978 and 1997, varying between 32.1% and 32.5%. The
first global-scale coral bleaching event took place in 1998 and affected almost
all coral reef locations. As a result, between 1997 and 2002, the average global
hard coral cover decreased from 32.5% to 30%. This amounted to a loss of
6.500 km
2
of coral, or 7.8% of all hard coral in the world over the course of
these five years. Because of the 1998 mass coral bleaching event, there has
been a marked increase in global monitoring efforts to determine the
consequences of this phenomena on coral reefs all over the world. Between
2002 and 2009, the average hard coral cover on a global scale recovered to
levels seen before 1998, reaching 33.3% in 2009. This indicates that many of
the world's coral reefs have persisted resilient and capable of regenerating in
the absence of severe global upheavals, despite the influence of local stressors.
The global average hard coral cover has been trending downward steadily
since 2009. Global hard coral cover decreased from 33.3% to 28.8% on
average between 2009 and 2018, losing 13.5% of its total global coverage
(GCRMN, 2021).
Mitigation measures to protect coral’s
There is no single way to save coral reefs; rather, numerous synchronised
actions must be made in order for corals to survive into the future. By
appropriately managing fisheries, outlawing destructive fishing and
addressing all pollution sources, threats to coral reefs can be locally reduced.
To reduce the likelihood of coral bleaching and acidification, efforts to keep
global warming below 1.5 ºC are crucial. Despite the fact that conversations

81. Page | 76
about the ocean are growing increasingly frequent at international climate
organisations like the United Nations, the negotiations on climate change are
proceeding slowly. The significance of ocean habitats, such as coral reefs,
must pick up steam and assume a more central position in climate mitigation
plans. The traditional economic structures must also change, and circular
economic principles must be adopted. To permit a drop in global temperature,
economic systems must quickly transition to a low-greenhouse gas emission
scenario. Benefits provided by coral reefs, which are currently ignored in
mainstream business and finance, should be included in a shift away from
current economic thinking. Hence it makes sense to approach maintaining and
restoring coral reefs as an asset, and to make long-term investments in their
preservation.
Conservation of coral reefs
There is still more that needs to be done in the future to conserve coral
reefs, as 20% of the world's coral reefs have already been lost.
 Creation of marine protected areas: One of the primary works in
conserving coral reefs is the development of Marine Protected Areas
(MPAs). Presently, across South, Southeast and Far Eastern Asia
there are 1,125 MPAs.
 Increasing awareness: As an additional resource for both students
and teachers of GCE Advanced Level Biology, IUCN Sri Lanka
published a book on coral reefs in 2003. It was written in each of the
three national languages.
 Reef stability: The greatest difficulty that coastal managers currently
face with regard to coral reef protection and management is possibly
adapting to climate change.
 Prevention of over-harvesting through legislation: All stony
corals, black corals, fire corals, and sea fans are legally protected in
India (Wildlife Protection Act, 1972). The 1993 Flora and Fauna
Protection Act in Sri Lanka provides legal protection for all stony
corals.
 Monitoring: Many organisations throughout the world keep tabs on
the condition of coral reefs. The Global Coral Reef Monitoring
Network (GCRMN), in collaboration with Reef Check and Reef
Base, coordinates projects to improve coral reef management through
knowledge sharing and capacity building.

82. Page | 77
Summary
 There are growing climate change scenarios, but they are still
incomplete, too vast in scope, and very unknown.
 Identification of thresholds is necessary for the health and longevity
of the reef ecosystem.
 To deal with several synergistic pressures, both spontaneous and
deliberate adaptations will be required.
 We do not yet know whether adaptation will be sufficient for the
continued existence of certain reef communities or of reefs as a
whole.
 So, there is a need to concentrate more on climate change research in
tropical areas, at smaller spatial scales, and on important factors like
ENSO, the behaviour of tropical cyclones, and regional variations in
sea level rise.
 Risk assessment should take precedence over lone predictions or
extremely wide uncertainty ranges.
 "Capacity-building" calls for thorough understanding of risk
(Pittock, 1999).
Conclusion
All ocean basins urgently require support and development of
conservation initiatives, but this may only be possible if temperatures stabilise
under low greenhouse gas emission scenarios. Without addressing non-
climate pressures that weaken reef resilience and runaway warming above 2
°C, coral reefs will have little chance of surviving. Major reef systems will
almost certainly not survive in the Anthropocene if these things happen. Coral
reef health in the future years will be a blatant sign of our ability to change the
above-mentioned policies and practises. The advantages of taking action
together to save coral reefs will be felt by all people on the planet because
these changes are favourable for the sustainability and health of the planet as
a whole. The strength of corals and zooxanthellae to adjust to these quick and
continuing changes has to be better understood. Yet, current data indicated
that corals and zooxanthellae are unable to adapt or acclimatise quickly
enough to keep up with the current elevatyed rate of warming in tropical
oceans. Changes in coral distribution are almost guaranteed to take place if the
mortality of reef-building corals keeps rising. Coral reefs worldwide will
experience a catastrophic future in the ensuing decades in our lifetimes if we
continue to pollute the ocean at such a high rate.

83. Page | 78
References
1. Bellwood DR, Hughes TP, Folke C Nyström M, et al. Confronting the
coral reef crisis. Nature. 2004;429(6994):827-833.
2. Burke L, Selig L. Reefs at risk in Southeast Asia., 2002.
3. Elias S, Alderton D. Encyclopedia of Geology. Academic Press, 2020.
4. Global Coral Reef Monitoring Network (GCRMN).
https://www.unep.org/resources/status-coral-reefs-world-2020.
5. Graham NA, Cinner JE, Norström AV, Nyström M, et al. Coral reefs as
novel ecosystems: embracing new futures. Current Opinion in
Environmental Sustainability. 2014;7:9-14.
6. https://www.noaa.gov/education/resource-collections/marine-life/coral-
reef ecosystems
7. IUCN. Guidelines for the Prevention of Biodiversity Loss Caused by
Alien Invasive Species. Gland: Switzerland, 2000.
8. Knowlton N. The future of coral reefs. Proceedings of the National
Academy of Sciences. 2001;98(10):5419-5425.
9. Pittock AB. Coral reefs and environmental change: adaptation to
what? American Zoologist. 1999;39(1):10-29.
10. Sivaperuman C, Velmurugan A, Singh AK, Jaisankar I, et al. (Eds.).
Biodiversity and Climate Change Adaptation in Tropical Islands.
Academic Press, 2018.
11. Sorokin YI, Sorokin YI. Nutrition of corals. Coral Reef Ecology, 1995,
326-368.
12. Tun K, Chou LM, Cabanban A, Tuan VS, Suharsono TY, Sour K, et al.
Status of coral reefs, coral reef monitoring and management in Southeast
Asia, 2005.
13. Veron JEN. New species described in Corals of the World. Townsville:
Australian Institute of Marine Science, 2002, 11.
14. Wildlife Protection Act India.
http://envfor.nic.in/legis/wildlife/wildlife1.html Wilkinson C. Status of
Coral Reefs of the World, Townsville, Australia: Australian Institute of
Marine Science, 1972, 1.
15. Wilkinson CC. Status of coral reefs of the world. Australian Institute of
Marine Science (AIMS), 2004.

84. Page | 79
Chapter - 6
Grindstone Reactions as a New Green Chemical
Approach



Author
Dr. Maher Mohamed Abed El Aziz
Department of Chemistry, Faculty of Education, University of
Tripoli, Tripoli, Libya

85. Page | 80

86. Page | 81

Chapter - 6
Grindstone Reactions as a New Green Chemical Approach
Dr. Maher Mohamed Abed El Aziz


Abstract
According to modern recommendations, avoiding solvents was
considered as a new approach worldwide. Usage of solvents usually associated
with environmental impacts and contamination. Our present study aimed to
prepare carboxylate salts under solvent-free conditions. Twelve salts of
organic acids have been prepared successfully using grindstone reactions in a
solid phase. Reactions under investigations were evaluated in terms of time,
percentage yield (%), and the released temperature as-well-as the violence of
the reaction. It was found that salts of oxalate, tartrate, and citrate easily
prepared within a shorter time (~ 1-4 min.) with a relatively high percentage
yield (~ 60-85%). The violence of the reactions was monitored by recording
the maximum temperature which reached 103 ᵒC after 2 min. for the reaction
of tartaric acid with NaOH. Aluminium salts were excluded due to the
insufficient reactivity of aluminium hydroxide towards carboxylic acids. It
was found that salicylic acid is the lowest reactive compound due to its
aromatic property, and therefore salicylate salts show the lowest percentage
yield (~50-70%). Acidity and basicity are the main operational factors
affecting the final product and its amount. The rate of changing temperature
with grinding time (ΔΦ,°??????/&#3627408474;??????&#3627408475;) was calculated and the reaction of citric acid
with NaOH has the highest ΔΦ value. Finally, the proposed procedure is
considered as good new water resources. Grindstone reactions were
characterized by simplicity, workability, applicability, efficiently in addition
to shorter life time for the preparation of various salts of organic acids.
Keywords: Grindstone, neutralization reactions, organic acids, a chemical
resource of water
Introduction
Salts of carboxylic acids are familiar and play an important role in so
many fields, for example pharmaceutical
[1]
, food processing
[2]
, textile
industry
[3]
, as-well-as preparation of the laboratory reagents
[4]
. From the

87. Page | 82
chemical point of view, salts of carboxylic acids, RCOO
-
M
+
, are ionic organic
compounds which are obtained by the reaction of carboxylic acid with reactive
metals, metal oxides, hydroxides, carbonates, or bicarbonate. The majority of
organic salts are soluble in water due to the presence of ionic bond, while alkyl
groups (R) cause insolubility in aqueous solutions
[5]
. Carboxylate anion (-
COO
-
) was described as hydrophilic or water-loving part in the salt, but alkyl
and/or aryl groups (R, Ar) are the hydrophobic or water-repelling part in the
molecule. Salts of carboxylic acids, like sodium salicylate, are an anti-
inflammatory agent
[6]
that is less effective than equal doses of aspirin in
relieving pain and reducing fever. However, individuals who are
hypersensitive to aspirin may tolerate sodium salicylate. According to
American Medical Association (AMA) of Drug Evaluations, salicylate
produces the same adverse reactions as aspirin, but there is less occult
gastrointestinal bleeding
[7, 8]
. Sodium or potassium oxalate is used in finishing
textiles and leather
[9]
. It is a good reducing agent
[10]
and it can be used as a
primary standard for standardizing potassium permanganate (KMnO4)
[11]
. In
the human body, calcium (Ca
2+
) and iron (Fe
2+
) react directly with oxalic acid
to form oxalates crystals in urine. This forming carboxylic acid salt can
accumulate as larger kidney stones that can stop the excretion of urine from
kidney. An estimated 80% of kidney stones are formed from calcium oxalate
[12]
. Magnesium (Mg
2+
) oxalate is 567 times more soluble than calcium
oxalate, so the latter is more likely to precipitate out when magnesium levels
are low and calcium and oxalate levels are high. Rochelle salt or sodium
potassium tartrate tetrahydrate (KNaC4H4O6·4H2O) is an odorless, colorless
white crystalline solid with a salty taste. It is the double salt of tartaric acid. It
is soluble in water but insoluble in alcohols. Commercially, Rochelle salt is
prepared in aqueous medium by the direct reaction between potassium
bitartrate and 0.5M Na2CO3 solution. Rochelle salt as an additive having the
symbol (E337) in food industry acts as emulsifier, stabilizer, buffer and
antioxidant in cheese products, margarine, jellies, jams, minced meat, and
sausage casings. Pharmacologically, it is used as saline cathartics (dose: 5 to
10 g for adults), therefore it can be used for the removal of toxic materials in
some cases of poisoning. Other applications include the preparation of
piezoelectric crystals, in the manufacture of mirrors; in the plating industry;
as a laboratory reagent; in the preparation of Fehling solution for the test of
aldehydes
[13]
and for delaying the quick-setting time of gypsum and cement
[14, 15]
. Sodium citrate (E331) is the sodium salt of citric acid. Like citric acid,
it has a sour taste. Like other salts, it also has a salty taste. It is commonly
known as sour salt and is mainly used as a food additive, usually for flavor or
as a preservative. According to the above mentioned applications and the

88. Page | 83
usage of carboxylate salts, it was noticed that salts of organic acids play an
important role in three main sectors
1) Pharmaceutical and medical industry.
2) Preservatives and food processing industry.
3) Laboratory chemicals or reagents.
Recently, the increase in demand for using salts of organic acids in
various industrial sectors encourages many chemists and researchers to
improve or enhance the preparation methods of these salts either at laboratory
or industrial scale. Preparation of carboxylate salts usually associates with
environmental issues and economic problems, especially with using solvents
which easily spread the chemical contamination. Therefore, avoiding the
usage of solvents during the preparation of carboxylate salts is the main target
of environmental chemists, where the best solvent is no solvent
[16]
. Although,
many organic compounds such as pyrazole chalcones
[17]
, α, β-unsaturated
carbonyl compounds (Claisen-Schmidt condensation)
[18]
, pyrimidine
derivatives (Biginelli reaction)
[19]
and spiro indol derivatives
[20]
were
synthesized by grindstone technique, but till now there is no trends in research
to prepare carboxylate salts using the same technique. Literature show that the
preparation of salts of carboxylic acid in aqueous medium is well-known, but
its preparation without the usage of solvents is less known. So, our present
work aimed to launch and evaluate the grindstone neutralization reaction
technique for the preparation of salicylate, oxalate, tartrate, and citrate salts by
the reaction with different alkalis in solid phase. Also, to study the chemical
and physical changes that takes place during the chemical reaction. A
comparison between different reactions was done in terms of the percentage
yield (%), reaction time, and the released reaction temperature to show the
structure behavior relationship for the investigated carboxylic acids.
Materials and Methods
Chemicals, tools and conditions
Salicylic acid (C7H6O3), oxalic acid (C2H2O4.2H2O), meso-tartaric acid
(C4H6O6), and citric acid (C6H8O7) were obtained from LANCASTER,
ENGLAND. Table (1) shows the Chemical, structural, and physical
characterization of various organic acids used in the present study. Pellets of
potassium hydroxide KOH, pellets of sodium hydroxide NaOH, calcium
hydroxide powder Ca(OH)2, and aluminium hydroxide powder Al(OH)3 were
obtained from SURE CHEM PRODUCTS LTD, ENGLAND. All the above
chemicals are analytical grade (≥ 99.90%) and dehydrated for 24 h in a
desiccator contains dry lumps of caustic lime (calcium oxide, CaO) before

89. Page | 84
using. Crystalline organic acids and alkalis were used in the solid phase
without further treatment. A clean porcelain mortar with pestle was used for
the neutralization reactions between organic acids and alkalis (grindstone
preparation of organic salts). An electronic balance with four digits was used
for weighing the solid reactants and products. The chemical reactions between
organic acids and alkalis were carried out in the winter at the laboratory
temperature ≈ 15±2 °C, and humidity = 83% under a good ventilated
atmosphere. Grindstone neutralization reactions are vigorous exothermic
reactions leads to evolution of dense fumes/vapors and different odors,
therefore the personal protective tools such as goggle, gloves, and the air filter,
were used to protect eyes, hands, and the breathing system respectively during
the experimental work. Also, the fuming cupboard was used for the very
vigorous reactions to avoid the danger circumstances.
Grindstone reactions
Different organic salts were prepared via the neutralization reactions
between organic acids and different alkalis using gram molar ratio. For the
preparation of the carboxylate salts, 0.10 Mole of the acid was reacted with
the corresponding molar ratio of the alkali and the reaction proceeds according
to the following general equations:
Dissociation of alkali: M(OH)n M
n+
+ nOH
-
…………………… .. (1)
Dissociation of an organic acid: nR-COOH nR-COO
-
+ nH
+
…… (2)
Formation of carboxylate salts
R-COOH + MOH R-COOM + H2O ……………………. ………... (3)
Organic acid and alkali were mixed together by grinding the reactants for
1-4 minutes using a mortar and pestle. During grinding process, the reaction
was monitored by the thermometer, and after completion of the reaction, the
product was subjected to drying into heating oven at 105 °C to constant
weight. The dry residue weighed and the percentage yield was calculated for
each individual salt by the equation:
% ????????????&#3627408466;&#3627408473;&#3627408465; (??????????????????&#3627408464;????????????&#3627408464;??????&#3627408473;)=
??????&#3627408474;&#3627408476;&#3627408482;&#3627408475;&#3627408481; &#3627408476;&#3627408467; &#3627408479;&#3627408466;&#3627408480;??????&#3627408465;&#3627408482;&#3627408466; (&#3627408468;)
&#3627408481;&#3627408476;&#3627408481;??????&#3627408473; ??????&#3627408474;&#3627408476;&#3627408482;&#3627408475;&#3627408481; &#3627408476;&#3627408467; &#3627408479;&#3627408466;??????&#3627408464;&#3627408481;??????&#3627408475;&#3627408481;&#3627408480; (&#3627408468;)
×100=
&#3627408474;
??????
×100 …(4)
After complete dryness, the chemical identity of the prepared compounds was
confirmed practically by measuring the melting point of the dry salt using
electric melting point instrument.

90. Page | 85
Table 1: Chemical, structural and physical characterization of various organic acids
Organic acids
Characters Salicylic acid Oxalic acid Tartaric acid Citric acid
Structural formula (SF)



Molecular formula (MF) C7H6O3 C2H2O4.2H2O C4H6O6 C6H8O7
Molecular weight (MW) ~ 138.12 g.mol
-1
~ 126.065 g.mol
-1
~ 150.00 g.mol
-1
~ 192.12 g.mol
-1

Classifications
Aromatic mono-carboxylic
(mono-hydroxyl)
Aliphatic di-carboxylic
(non-hydroxyl)
Aliphatic di-carboxylic
(di-hydroxyl)
Aliphatic tri-carboxylic
(mono hydroxyl)
Number of carbon atoms 7C 2C 4C 6C
Number of COOH group 1 2 2 3
Number of OH group 1 0 2 1
Melting point (MP), ºC 158.6 ᵒC 101.5 ᵒC 165.5 ᵒC (meso) 156 ᵒC
Physical state (at 25 ºC) Crystalline solid Crystalline solid Crystalline solid Crystalline solid
Density (g.cm
-3
) 1.443 1.653 1.79 1.67
pKa-values pKa1 = 2.97 pKa2 = 13.82 pKa1 = 1.27 pKa2 =4.27 pKa1 = 2.89 pKa2 =4.40 pKa1 = 3.13 pKa2 = 4.76 pKa3 = 6.40

91. Page | 86
Results and Discussions
Preparation of salicylates, oxalates, tartrates and citrates
The reactions between organic acids and different alkalis to form various
carboxylate salts has been carried out using grindstone technique, and the
results of the reactions were summarized in Table (2), from which it was found
that no reaction could proceed by direct contact between the reactants in solid
phase without grinding, and this can be explained by the resulted friction
between small molecules of the reactants from the mechanical grinding
process is the initiating power of the neutralization reactions
[21]
and the
transferred energy from the pestle to molecules is the driven force of the
reaction
[22]
. It was noticed that aluminium hydroxide does not undergo
grindstone neutralization reaction with any acids used in this study up to 10
min. grinding time, and this is maybe attributed to the fact that aluminium
hydroxide Al(OH)3 is considered as a Lewis acid (producing H
+
) of the lowest
alkalinity that dissociates according to the following equations:
Al(OH)3 + H2O [Al(OH)4]
-
+ H
+
………………………………… (5)
H
+
+ H2O (H3O)
+
………………………………………………… (6)
(H3O)
+
+ [Al(OH)4]
-
[H3O][Al(OH)4] …………………………… (7)
The final product of the following overall reaction equation shows the
actual structure of aluminium hydroxide is a coordinated complex having the
formula [H3O][Al(OH)4] not Al(OH)3 as follows:
Al(OH)3 + 2H2O [H3O][Al(OH)4] ………………………………… (8)
Aluminium ion (Al
3+
) combines with three hydroxide anion (3OH
-
) and
two water molecules via the formation of stable hydronium
tetrahydroxoaluminate (III) complex as shown in equation (7 & 8)
[23]
.
Unfortunately, aluminium hydroxide exists as a stable coordinated complex
instead of free available hydroxide anion form, and hence it was excluded for
further or more investigations due to its low reactivity towards organic acids
[24]
. Accordingly, it was concluded that aluminium salicylate, oxalate, tartrate,
and citrate cannot be prepared using direct grindstone neutralization reactions.
Besides, Table (2) refers to the presence of three types of grindstone
neutralization reactions, vigorous, moderated and weak reactions.
Effervescence, evaporation, bubbles, and sudden increase in temperature were
observed with vigorous reactions, but moderated reactions are less violent than
vigorous reactions. Grindstone neutralization reaction of oxalic, tartaric, and
citric acids with strong alkalis (NaOH & KOH) are vigorous reactions, while
the reaction of salicylic acid with the same alkalis are moderated reactions.

92. Page | 87
The last observation can be attributed to the fact that aromatic acids like
salicylic acid are less reactive than aliphatic one
[25]
. The lone pair of electrons
of carboxylate anion (-COO
-
) in salicylic acid are delocalized and distributed
on the benzene ring forming at least four canonical structures of carboxylate
anion. Electronic resonance between carboxylate and benzene ring in salicylic
acid supports the aromatic character of the molecule, and hence the stability
of salicylic acid. The more aromatic character, the more stability of the
molecule, and the low reactivity will be and the vice versa
[5]
. The low
reactivity of salicylic acid towards alkalis was confirmed by
1) The relatively low percentage yield (practical) of the product.
2) The relatively more time for the reaction to begin.
3) Slight increase in temperature.
Again, resonance and aromatic character of salicylic acid can explain the
gap between the theoretical and practical values of the percentage yield for the
reaction of the acid and alkalis. Mostly, reactions of investigated organic acids
with calcium hydroxide can be described as moderated reactions and this are
logically accepted due to decreasing in the basicity or alkalinity. The relative
degree of violence of the reactions can be observed depending upon
1) The recorded maximum temperature.
2) The grinding time.
3) The percentage yield of the product.
From Table (2) it was concluded that sodium, potassium, and calcium
salicylate have been prepared successfully using grindstone neutralization
reaction in shorter time (4-6 min.) with percentage yield up to more than 70%.
Again, aluminium salicylate cannot be prepared using the proposed technique
due to the low basicity of Al(OH)3, and the low reactivity of salicylic acid.
The expected reaction equations for the preparation of sodium, potassium and
calcium salicylate are:
C7H6O3 + NaOH → C7H5O3Na + H2O ……………………………… . (9)
C7H6O3 + KOH → C7H5O3K + H2O ………………………………… (10)
2C7H6O3 + Ca(OH)2 → [C7H5O3]2Ca + 2H2O ……………………… . (11)
Theoretical and practical values for the reactions of oxalic, tartaric, and
citric acids with strong alkalis are closely related to each other, while there are
differences for the reactions with calcium hydroxide due to the low basicity of
calcium hydroxide. According to the recorded maximum temperature and the
practical percentage yield, grindstone neutralization reaction of organic acids
with strong alkalis can be ordered as follows:

93. Page | 88
(Tartaric acid + MOH) > (Citric acid + MOH) > (oxalic acid + MOH) >
(salicylic acid + MOH)
The above sequence may reflect the relative acidity and reactivity of the
three acids towards grindstone neutralization reactions. Although the pKa
values of the three acids prove that oxalic acid is the most acidic and citric
acid is the lowest acidic one, grindstone neutralization reactions proves that
acidity is not the only factor that playing role in the behavior of the acids
during the reactions. Tartaric acid (di carboxylic acid) has the maximum
percentage yield and recorded temperature and this may be due to the side
reactions of the two hydroxyl groups (2OH) at C2 and C3 with alkalis forming
sodium and/or potassium alkoxides (R-O-Na) compounds besides the main
neutralization reactions of the carboxyl groups. Although citric acid contains
three acidity sites, but it has not the highest released energy compered to
tartaric acid, and this is may be attributed to the steric hindrance associated
with the spatial configuration of citric acid. The higher steric hindrance, and
hence the more crowding will be the lower availability of acidic center and
vice versa. Sodium, potassium, and calcium oxalate can easily prepare in high
percentage yield (> 80.8% with KOH) by the grinding technique in a short
time (1.5-3 min.) due to the aliphatic nature and the reactivity of the acid
according to the following equations:
C2H2O4 + 2NaOH → C2Na2O4 + 2H2O + Energy …………………… (12)
C2H2O4 + 2KOH → C2K2O4 + 2H2O + Energy …………………… . (13)
C2H2O4 + Ca(OH)2 → (CO2)2Ca + 2H2O + Energy ………………… . (14)
Tartaric and oxalic acids have the same acidic nature, and are aliphatic di
carboxylic acids
[26]
that can easily produce sodium, potassium, and calcium
salts in the same manner with high percentage yield by means of grindstone
technique. Tartrate salts can be prepared according to the following equations:
C4H6O6 + 2NaOH → C4H4O6Na2 + 2H2O + Energy ………………… (15)
C4H6O6 + 2KOH → C4H4O6K2 + 2H2O + Energy ……..…………… (16)
C4H6O6 + Ca(OH)2 → (C4H4O6)Ca + 2H2O + Energy ……………… (17)
The results show that the reaction of tartaric acid with strong alkalis is
vigorous and highly productive with short grinding time (2 min.). Citrate salts
has been obtained by the grindstone neutralization reaction of citric acid with
hydroxides of alkali and alkaline earth metal only. Citrate formation can be
expressed as follows:
C6H8O7 + 3NaOH → C6H5O7Na3 + 3H2O + Energy………………… (18)

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C6H8O7 + 2KOH → C6H5O7K3 + 3H2O + Energy…………………… (19)
2C6H8O7 + 3Ca(OH)2 → (C6H5O7)2Ca3 + 3H2O + Energy………….. (20)
Water as a by product of the reaction and the physically adsorbed water
molecules have been evaporated as a result of the released energy. The above
neutralization reactions were initiated by grinding and an enhancement was
introduced into the reaction through the first tiny amount of water produced
during the reactions. This infinitesimal amount of produced water can
complete the reaction by ion-exchange property between acids and bases.
Identity of the prepared salts was confirmed by measuring the melting points,
and the results show that the measured melting point of the prepared salts and
the recorded values in literature are nearly the same.
Table 2: Results of grinding reactions between various organic acids and alkalis
Violence
Maximum
Temperature
(°C)
Grinding
Time
(min.)
% Yield
Reaction Mixture
Practical Theoretical
Moderated 33 4 70.20 89.83 Salicylic acid + NaOH
Moderated 30 4 70.73 90.68 Salicylic acid + KOH
Weak 17 6 50.64 89.70 Salicylic acid + Ca(OH)2
No reaction Nil 10 0.00 89.03 Salicylic acid + Al(OH)3
Vigorous 77 1.5 77.80 78.82 Oxalic acid + NaOH
Vigorous 70 1.5 80.89 82.09 Oxalic acid + KOH
Moderated 30 3 60.65 78.00 Oxalic acid + Ca(OH)2
No reaction Nil 10 0.00 74.65 Oxalic acid + Al(OH)3
Vigorous 103 2 84.00 84.35 Tartaric acid + NaOH
Vigorous 100 2 85.22 86.18 Tartaric acid + KOH
Moderated 40 4 61.97 83.89 Tartaric acid + Ca(OH)2
No reaction Nil 10 0.00 82.18 Tartaric acid + Al(OH)3
Vigorous 89 1 81.67 82.70 Citric acid + NaOH
Vigorous 85 2 84.05 84.93 Citric acid + KOH
Moderated 35 3 66.32 82.14 Citric acid + Ca(OH)2
No reaction Nil 10 0.00 80.01 Citric acid + Al(OH)3
Laboratory temperature ≈ 15±2 °C.

The rate of change of temperature with time
The variations of temperature during the grindstone neutralization
reactions between organic acids and alkalis have been studied carefully, and
the rate of change of temperature with grinding time ( was defined as:
…………………… (21)

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Where are the temperature differences between the final temperature
and the initial temperature (= 15 ᵒC). is the difference between final
and initial time ( The values of (were calculated for the
active reactions between organic acids and alkalis, and the results were
presented in Figure (1), from which it was noticed that all investigated
reactions can be classified into three mean categories as follows:
1) Reactions that have the highest rate of change of temperature with
time (highest value). The reaction of citric acid with sodium
hydroxide represents this type of reaction ( ).
2) Reactions that have the medium rate of change of temperature with
time (medium value). The values of these types are in the
range 35-44 and these reactions include the reaction of
 Oxalic acid with NaOH and KOH.
 Tartaric acid with NaOH and KOH.
 Citric acid with KOH only.
3) Reactions that have the low rate of change of temperature with time
(low value), where value is below , and these
include the reactions of
 Salicylic acid with strong alkalis.
 Oxalic acid, tartaric acid and citric acid with Ca(OH)2.

Fig 1: The rate of change of temperature with time for different grindstone
neutralization reactions

96. Page | 91
The average rate of raising temperature is about ≈ 4.125 ᵒC/min. or 060.0
ᵒC/s for the reaction with NaOH and KOH. According to the above-mentioned
results, values for different alkalis and acids take the following sequences:
( for NaOH >( for KOH > ( for Ca(OH)2
With the exception of (citric acid with NaOH):
( for Tartaric acid > ( for Oxalic acid > ( for Citric acid > (
for Salicylic acid.
The first sequence is in agreement with the alkaline properties of these
bases. For organic acids, the second sequence is in agreement with the results
of citric acid which has a more crowded spatial configuration leading to
shortage in the availability of acidic sites in the molecule. The reaction of citric
acid with NaOH (exception) has the highest value of , this is may be due
to the small size of sodium ion (98 pm)
[27]
which can easily overcome the
steric hindrance and crowding in citric acid molecule. The smallest size of
sodium ion can easily reach and facilitate the reaction with the three carboxylic
groups in citric acid to form the sodium citrate salt with three acidic centers.
From the above mentioned observations and according to the results in Figure
(1) it highly recommended using the grinding technique for the preparation of
sodium/potassium citrate, sodium/potassium tartrate, and sodium/potassium
oxalate in dry state. The process seems to be simple, having short time, having
high percentage yield, and having high ( value. Elevated temperature can
help in producing a solid salt in dry state. Also, it highly recommended using
the grinding technique for the preparation of calcium citrate, calcium tartrate,
calcium oxalate, and sodium/potassium salicylate in wet state, where these
reactions are having the lowest values of (. The elevated temperature in
these cases is not enough to reach the complete dryness state.
Grindstone reactions as a source of water
From the chemical equations of oxalic, tartaric, and citric acid with strong
alkalis, water was produced as a byproduct of the reaction. So, grindstone
neutralization reactions of carboxylic acids can be considered as new water
chemical resources for places suffer from the scarcity of water like desert or
moon. For astronauts, water is very big problem and the grindstone
neutralization reactions of carboxylic acids maybe solving it by a simple
chemical reaction. This reaction was completed within shorter time period (~
1-2 min.) to produce a reasonable amount of water, moreover the amount of
heat evolved from the reaction easily evaporate the produced water. This
proposed chemical reaction with some of engineering modifications or designs

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may be leads to a new instrument that can condense and collect the water vapor
in a receiving reservoir. The amount of water produced from each vigorous
chemical reaction was calculated from the following mass balance equations:
Oxalic acid: (each 85g reactants → 18 g of water)
C2H2O4 + 2NaOH → C2Na2O4 + 2H2O + Energy …………………… (22)
(90 g) (80 g) (134g) (36g)
Tartaric acid: (each 115g reactants → 18 g of water)
C4H6O6 + 2NaOH → C4H4O6Na2 + 2H2O + Energy ………………… (23)
(150 g) (80 g) (194 g) (36 g)
Citric acid: (each 104 g reactants → 18 g of water)
C6H8O7 + 3NaOH → C6H5O7Na3 + 3H2O + Energy ………………… (24)
(192 g) (120 g) (258 g) (54 g)
The above mass balance equations prove that oxalic acid is the mass
favored compound that contain the minimum mass to produce the same
amount of water. To produce one mole of water (18 g), we need ½ moles (45
g) of oxalic acid to react with one mole (40 g) of NaOH. Besides the reaction
temperature (77 ᵒC) is sufficient to evaporate the produced water molecules.
We think that 36 g (2 moles) of water can save the astronauts' life for one day
on the moon. It is great chemical reaction.
Conclusions and Recommendations
In this work, grindstone neutralization reactions between carboxylic acids
(salicylic, oxalic, tartaric, and citric acids) and different alkalis were examined
for the preparation of salicylate, oxalate, tartrate, and citrate salts. According
to the present study, it is highly recommended to use NaOH, and KOH for
undergoing the neutralization reactions with aliphatic or aromatic acids.
Salicylate, oxalate, tartrate, and citrate salts can easily prepared using
grindstone neutralization technique with shortest time (1-4 min.) and high
percentage of yield (70-85%). The reaction of oxalic, tartaric, and citric acids
with strong alkalis can be described as vigorous reactions having the highest
rate of changing temperature with grindstone time. The investigated reactions
produce water as a by product in a reasonable amount, so it would be
considered a new chemical source of water for astronauts in the space. The
research proposed and recommended to introduce some engineering
modifications to the grindstone neutralization reactions to obtain the released
water from the reaction. In general, the process seems to be very simple, do
not need tools more than mortar and pestle, having good yield in shorter time,
in addition to it is solvent free process.

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References
1. Deepak Gupta, et al. Salts of Therapeutic Agents: Chemical,
Physicochemical and Biological Considerations. Molecules.
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2. Nanditha Murali, Keerthi Srinivas, Birgitte K Ahring. Biochemical
Production and Separation of Carboxylic Acids for Biorefinery
Applications. Fermentation. 2017;3(22):1-25.
3. Deshuai Sun, et al. Application of liquid organic salt to cotton dyeing
process with reactive dyes, Fibers and Polymers. 2017;18(10):1969-1974.
4. Dorian AH Hanaor, Marco Michelazzib, Cristina Leonellib, Charles C
Sorrell. The Effects of Carboxylic Acids on the Aqueous Dispersion and
Electrophoretic Deposition of ZrO2. Journal of the European Ceramic
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5. John D Roberts, Marjorie C Caserio. Basic Principles of Organic
Chemistry, Second Edition, W.A. Benjamin, Inc., 1977. ISBN 0-8053-
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6. Preston SJ, et al. Comparative analgesic and anti-inflammatory properties
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12. Coe, Evan, Worcester. Kidney stone disease. The Journal of Clinical
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14. Maximilienne Bishop, Andrew R Barron. Cement Hydration Inhibition
with Sucrose, Tartaric Acid and Lignosulfonate:  Analytical and
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15. International Workshop on Calcium Sulfoaluminate Cements. Murten,
Switzerland, 2018 June. https://www.journals.elsevier.com/cement-and-
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Shafi Gadwal. Highly Selective Claisen-Schmidt Condensation
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19. Kumar JS, Shabeer TK. Multicomponent Biginelli Synthesis of 3,4-
dihydropyrimidin-2(1H)-ones by grindstone technique and evaluation of
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20. Sachdeva H, Sharma S. Green Preparation and Structure Elucidation of
Spiro Indole Derivatives Using Grindstone Technique. MOJ Biorg Org
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23. Geoff Rayner-Canham, Tina Overton. Descriptive Inorganic Chemistry,
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27. https://chem.libretexts.org/Courses/Mount_Royal_University/Chem_12
01/Unit_2._Periodic_Properties_of_the_Elements/2.08%3A_Sizes_of_
Atoms_and_Ions)_11

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102. Page | 97
Chapter - 7
Range Over on Brute Creation white Tigers along
with others of Maitri Baag Zoo Bhilai,
Chhattisgarh



Author
Roli Ojha Mishra
Department of Life Science (Zoology), Shri Shankaracharya
Professional University, Bhilai, Chhattisgarh, India

103. Page | 98

104. Page | 99

Chapter - 7
Range Over on Brute Creation white Tigers along with
others of Maitri Baag Zoo Bhilai, Chhattisgarh
Roli Ojha Mishra


Abstract
Maitri Baag Zoo is found near Maroda tank, Bhilai, Chhattisgarh. The
work towards the current investigates to range over the animalia of Maitri
baag zoo. Observe was the first proposal of Maitri baag zoo to prepare
checklist of 24 species representing 22 genera under 12 families. Zoos are
increasingly introducing digital technologies to enhance visitor’s experience
of viewing animals and promote the welfare and wellbeing of captive
animals. A Maitri Baag Zoo Cum children’s park is well maintained by the
Bhilai Steel Plant. The focus attention of the Zoo is exotic animals and avian
species, lake, toy trains and others. The musical fountain, situated on the
island in the artificial lake in Maitri baag zoo. White Tigers are the
allurement of the zoo. Every year a flower show is organized here. In the
Maitri baag zoo, among the restricted animals some are endangered species
which are conserved and are helpful for the change for the better of those
animals.
Keywords: Maitri baag zoo, Chhattisgarh, Bhilai steel plant, toy train,
musical fountain, lake, white tigers
Introduction
Early in 1957,
[1]
the existing area of Maitri Baag used to be a forest
covered with trees of different varieties, such as sakhua, sagwan, mahua,
arjun and palas etc. During past years Maitri Baag is a "Friendship Garden"
established as symbol of India-Soviet Union friendship
[2]
. It laid the
foundation in the 1972. It was established and sustain by Bhilai steel plant
[3]
.
It is the tremendous and earliest zoo of Chhattisgarh. Maitri baag zoo is
located at Maroda tank which is 12 km from Durg city of Durg-Bhilai
district of Chhattisgarh. The Maitri baag zoo is situated in the heart of Bhilai
City and spread over an area of 131.00 acres of land in center of Steel
Township. Previously it was started with some donated animals like deer,

105. Page | 100
monkeys by Forest department and over the years it has developed in a small
zoo. The zoo is famous for its Royal Bengal Tigers and White Tigers which
are endangered species. Maitri Baag Zoo also support conservation of
endangered species, which have no chance of survival in wild, a last chance
of survival through coordinated breeding under ex-situ conditions and raise
stocks. Currently it is place of residence of rare and endangered species of
wild life and colorful birds. To make safe the rich diversity of nature for
future generation and also ensure the earth in which human values are
protected and conserve the Flora and Fauna. The part of the Maitri baag zoo
has evolved to prioritize research, education and conservation
[4]
. The main
aim of the zoo is in line with national zoo policy, which is to astonishment
and justifies the national efforts in saving of the rich biodiversity of the
country, particularly the wild animals. Visitant or visitors convenience also
available in zoo, zoo have proper road with proper sign or mark for
particular parrock has been show to avoid confusion. Proper educative
signage, with different species, tree, saving earth slogans are in the way
which automatically give educative diet to visitors. Make sheds at different
location for the visitors with nearby drinking water. Facilities are also given
to physically challenged (wheel chair). Visitor has to provide all facilities
like benches, toy train,

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First aid box, toilets etc. Hyena and Nilgai which are not only develop in
Chhattisgarh but all over the country. As they are protected here so their
population can be increased and they can come in normal population
[5]
. Zoo
is famous for its Royal Bengal Tigers and White Tigers which are
endangered species
[6]
. White tigers are a infrequent generation and it’s
believed that a white tiger hasn’t been seen in the wild for around 50 years,
making them put in danger. When they are in the ferocious they would be
found throughout India. Although, today we are more likely to find a white
tiger in a zoo or wild life reserve around the world. The white tiger emanate
from Bengal tigers but has a unique difference of color. White tigers are also
generally alluding to as white Bengal tigers, look like Bengal tiger, but
shortage of orange hue. The whiteness of white tigers to their fur is achieved
by a genetic defect which results in white tigers losing a pigment called
pheomelanin
[7]
, which gives Bengal tigers the orange color in their fur. The
absence of this pigment gives white tigers the unusual and unique white
color. An alternative component is how infrequent the white tiger is-the
coloration is dependent on a defective, recessive gene which is passed to
them from their parents. The scientific name of white tiger is Panthera
Tigris Tigris. The white tiger has suffered from health intricacies due to
crossbreeding these include crossed eyes, cleft pallets, scoliosis and genetic
problems such as Down Syndrome. The white tiger is accepted to be the
second-largest tiger - the Siberian tiger is believed to follow after.

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Reason why white tigers endangered: Award the chase and the loss of
habitat is the big cause of White Tigers endangered. At the present time
white tigers in a zoo or wild life reserve around the world for existence.
Attempt to re-establish the white tiger were done so by intentionally
crossbreeding to maintain the tiger’s white coloration. This is the only way
to make sure the white tiger succeeds, but it does come with health
intricacies. As researcher identified these problems with crossbreeding, work
has begun to try and cross-breed pairs of Bengal tigers, with each one
holding the gene that creates the white tiger. It’s accepted that probability
rate would be a 25 percent chance of a pregnancy resulting in a white tiger.
This way will help increase the population of white tigers more healthily.
Total population of white tigers: This infrequent color mutation called
leucism, which also take place in many other animals, appears in perhaps
one in 10,000 tigers in the wild. The mutation results from the mating of two
tigers that carry the recessive allele that produce white fur in their
offspring. Only around 200 white tigers survive in the world today.
Conservation: The white tiger is record as put at risk under ICUN
(International Union for Conservation of Nature) and is severely
endangering therefore the only remaining species are in captivity. The white
tiger isn’t the only tiger put at risk as Records show that around 100,000
tigers were found in Asia during the beginning of the 1900s - today is a
different story with no more than 8,000 remaining in the wild. It’s estimated
that 2,000 of this number are Bengal tigers; white tigers are not included as
they remain in restraint.

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Nourishment of white tiger: White tiger is similarly to the Bengal tiger
in the same sense that they spend most of the day sleeping, though trapping
for food during the night time. Their diet consists of large carnivores such as
pig, goat, deer etc. Although, when white tigers are in zoos or wild life
reserve they are usually fed meat, horse flesh and sometimes kangaroo flesh
too.
The behavior of the white tiger: White tigers, similarly to other tiger
species similar to live alone and are a antisocial animal. They live like this as
it would make it easier for them to chase in the wild, as they usually sneak
up on their prey. Although, during copulating season male white tigers
enclave would overlap with females to find a partner to copulate with. White
tigers have been known to have magnificent audience and vision which
makes hunting in the dark a lot easier for them. White tigers aren’t night-
loving; however, they would have done most of their hunting at night for a
more triumphant result.
Habitat of white tiger: The white tiger is in the wild its favor habitat is
in the Asian and Indian subcontinent, same as the Bengal tiger. A white
tiger's habitat would exist of equatorial forests, mangrove swamps and
grasslands, their habitat would also include abundance of freshwater within
reach. They also need cover to be able to stay hidden as well as plenty of
trees. In their natural habitat, a white tiger has a large enclave, ranging from
20 to 30 square miles. White tigers wander openly in their habitat in the
Asian and Indian subcontinent; they would frequently find it hard to chase.
Their white coloration made it difficult for them to successfully pursue for
food, making most of their chase unsuccessful.
Biological clock of white tigers: Life start as a cub and a mother white
tiger can give birth up to three cubs at a time. For two months the cubs feed
milk from their mother, shortly after they start to be removed. At 18 months
of age, the cubs start to be initiate to chase on their own, although they still
rest close to their mother until they extend two years of age. When they
grown up white tigers are very crude, they mark their patch or mark with
urine or by clawing marks on trees. These marks are only for them and no
other tiger can undertake. White tigers standard dotage is between 13 and 20
years, In spite of the fact it is dependent on them being in imprisonment.

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History of white tigers: In the time period of 1915, a white tiger cub
was seized and was held slave for five years, through in due course died. It’s
assumed that the white tiger was overwhelmed afterwards and was given to
King George V of England as a gift. In the midst of 1920 to 1930, it’s
evaluated that 15 white tigers were killed. Famous white tiger come first in
1951, the male white tiger who’s named Mohan and was found in the wild in
India. It’s trusted that the tiger was arrested and kept in Maharajah’s palace
in the courtyard. Later crossbreed with female tigers to help produce more
white tigers. Mohan lived for 19 years and is trusted to be the source of all
the 200 white tigers that persist in the world presently.
Manifestation of human being and white tigers: Human being play an
important role to crossbreeding of white tigers since they were brought into
custody, despite the fact that has been ethical probe as sometimes this can be
carried out for profit. Before 50 years when white tigers were wandering the
wild, humans played a big part in them pass from sight by trapping them,
making them lose lots of their natural environment and eventually would end
in them vanish from the wild. Sad to say it doesn’t stop here as Bengal tigers
have been familiar to enter human surrounding more frequently which
results in them being killed. In spite of, reduce in numbers; it was made
unlicensed to kill them. Maitri baag Zoo naturalize the spaces, distinguish
their animals and produce amazing experiences for their human visitors
[8]
.
When visitors stand before a reveal their look takes in much more than
animals posing in the middle of luxuriant vegetation
[9]
.

110. Page | 105

More About Maitri baag zoo animals and birds: Previously some
animals like Elephants, Asiatic lion, Guniea pig, etc. were also saved in the
Maitri baag zoo but in recently the animals which are kept are given in the
Table-1.
Table 1: Name of Animals
Family Species Common name
Varanidae Varanus salvator Water monitor lizard
Testudinidae
Geochelone elegans Tortoise
Geochelone elegans Star tortoise
Hystricidae Hystrix indica Indian porcupine
Bovidae Boselaphus tragocamelus Nilgai
Felidae
Panthera tigris Bengal tiger
Panthera tigris tigris White tiger
Hyaena hyena Striped Hyena
Canis aureus indicus Jackal
Panthera pardus Leopard
Paradoxurus hermaphroditus Toddy cat

Cervidae
Antilope cervicapra Black bug
Antilocapra americana Antelope
Muntiacus Barking deer
Axis axis Spotted deer
Ursidae
Melursus ursinus Sloth bear
Ursus thibetanus Himalayan bear
Pythonidae Python molurus Python
Muridae Mus musculus White mouse
Cercopithecidae
Bonnet macaque Bonnet
Macaca mulatta Rhesus

111. Page | 106
Semnopithecus schistaceus Common langur
Alligatoridae Gavialis gangeticus Alligator
Crocodilae Crocodylus niloticus Crocodile


The animals are nourishing in the zoo according to their habit
[10]
.
Khichdi is given to the herbivores which include pumpkin, rice, wheat bran,
pulses, soybean, corn flour, salt, jiggery, etc. The carnivores are given flesh
but first sterilized by immerse in boiling water and then given to the animals.
Providing the complete nourishment to all the animals. These all ingredients
are measured before cooking and fixed amount of the ingredients are added
in the Khichdi. There is a specific amount of food for each animal like 45kg
of grams given to all the dears in one day, while one crocodile has given
1.5kg of fish in one day etc. In one day 220 kg of flesh and 25 kg of fish is
required. In table 2 have given the food supply to the animals and birds, total
members in which male, female and young included and its types of
enclosure or compound.
Table 2: Food supply to the animals, birds and its enclosure
Species Feed Item
Total
members
Enclosure
Adjutant Stork Fresh fish 1 Fence enclosure
Pelican and Indian
duck
Fresh fish 10+3 Fence enclosure
Ghariyal Fresh fish 4 Open enclosure.
Python Live chicken 10 Close cage.
Budgerigar Leafy Vegetable & Grains 8 Close cage.
Cockatiel Fruit, Leafy vegetable & grain 42 Close cage.
Parrot, Pigeon,
Turkey
Fruit, vegetable & grain 26,20,1 Close cage.
Spotted deer
Barking deer and
Concentrate mesh and green grass
13
1
Open enclosure.

112. Page | 107
Sambar deer 43
Nilgai Concentrate mesh and green grass 6 Open enclosure.
Black buck Concentrate mesh and green grass 10 Open enclosure.
Royal Bengal tiger
(White)
Goat meat 6
Open
enclosure/Cage
Lioness Goat meat 1 Open enclosure
Leopard Goat meat 2 Close enclosures.
Hyena Goat meat 3 Open enclosure
Crocodile Goat meat 1 Open enclosure.
Small Palm Civet Goat meat, milk & rice 5 Close cage.
Porcupine Nuts, rice & vegetable 1
Open
enclosure/Cage
Common Languor
Nut, gram, banana, vegetable &
cooked rice
2 Closed cage
Macaque Bonnet &
Macaque Rhesus
Nut, gram, banana, vegetables
and cooked rice in milk
5+11 Closed cage
EMU
Nut, Broiler finisher Layer feed,
Banana, Vegetable
3 Open enclosure.
Sloth and
Himalayan Bear
Milk, jagri, cooked rice, fruit
honey, khiri
2+2 Open enclosure.
Peacock Grams and vegetable 8 Open enclosure.
Owlet Forest
Spotted
Goat meat 2 Close cage.
Love birds and
Kite
Gram, fruit & vegetable 35+8 Close cage.
Jackal Goat meat 8 Closed enclosure


By the support of Dr. Dubey, Veterinary Doctor and Mr. Gopichand, the
Head Caretaker, Mr. Rajat Darsariya, the Assistant manager of the zoo. It is
very helpful to perceive about birds and animals.

113. Page | 108
The animals are in a good condition and even it was known that one
white tiger is 21 years old and it is serving with good health while the
common age of tigers are 15-17 years.
Those birds species which are put in danger and threatened are kept in
pair under monitoring in the zoo so that there number can be increased and
come in normal number
[11]
. In Maitri baag zoo only those birds are kept
which are capable to sustain or survive in the particular environment of the
zoo cause the change in ecological impact on the birds. Zoos provide
information to the visitors about the birds and animals and motivate to save
them. Maitri baag zoo is famous in Chhattisgarh. In Table-3 the bird’s
family, species and their common name given.
Table 3: Name of the Birds and Their Species Name
S. No. Family Species Common name
1. Dromaius Dromaius novaehollandiae Emu
2. Anatidae Bucephala albeola Indian duck
3. Accipitridae Milvus migrans Kite
4. Ciconiidae Leptoptilos dubius Adjutant stork
5. Columbidae Columba domestica Pigeon
6. Psittaculidae
Agapornis nigrigenis Love bird
Psittacula kramer Parrot
7. Phasianidae
Meleagris gallopavo Turkey
Pavo cristatus Peacock
8. Cacatuidae Nymphicus hollandicus Cockatiel
9. Pelecanidae Pelecanus onocrotalus Pelican


The Zoological Survey of India (ZSI), formed on 1916 by the Ministry
of Environment, Forest and Climate Change of the Government of India as a
leading Indian organization in zoological research and studies to promote the

114. Page | 109
survey, Examine and research of the animals in the country
[12]
. Many of the
birds are exotic. All the birds are kept in pairs so that their breeding is not
stopped in the zoo
[13]
. Endanger species of Birds of Asia identified that one
quarter of all bird species in Asia were a protection cover
[14]
.

Animals mortality: Mortality means the number of deaths in particular
and in one time period. Mortality is another term for death. A mortality rate
is the number of deaths due to a disease divided by the total population
[15]
.
There are two types of mortality
a) Absolute mortality: The number of deaths under optimum
conditions.
b) Realized mortality: The number of deaths when stressful
environmental pressures come into play.
Table 4 shows the animal mortality of Maitri baag zoo.
Table 4: Mortality of Animals
S.
No.
Animal Name
Common
name
Sex
Date of
Death
Reason of Death by
Postmortem report
1. Agapornis nigrigenis Love bird F 15-04-2017 Enteritis
2. Macaca mulatta
Macaque
Rhesus
M 22-04-2017 Hepatitis
3. Pavo cristatus Peafowl F 28-04-2017 Peritonitis
4. Macaca mulatta
Macaque
Rhesus
F 26-05-2017 Old age feebleness
5.
Semnopithecus
schistaceus
Common
Languor
F 25-06-2017 Old age feebleness
6. Pavo cristatus Peafowl F 11-08-2017
Necrosis of oesophagus
and gizzard.
7. Pavo cristatus Peafowl M 05-09-2017 Cirrhosis of liver
8. Hyaena hyena Hyena M 21-10-2017 Old age feebleness

115. Page | 110
Stripped
9. Macaca mulatta
Macaque
Rhesus
M 21-10-2017 Old age feebleness
10.
Paradoxurus
hermaphroditus
Toddy cat M 20-01-2018 Old age feebleness
11. Panthera tigris tigris White Tiger M 01-09-2022 Cancer

A nine-year-old male white tiger named ‘Kishan’ died of cancer at Maitri
Baag zoo in Durg Chhattisgarh. Kishan was treated for cancer under
veterinarians from Maitri baag and wildlife specialists from Anjora Veterinary
Hospital in Durg, Out of the five white tiger cubs; three were given to the
Rajkot Zoo in Gujarat in exchange for a pair of lions. At present, the Maitri
Baag zoo has five white tigers, official said in The Times of India
[16]
.
Result and Discussion: The investigation of Maitri Baag zoo have 24
species representing 22 genera under 12 families. Accordingly them, each an
everything have aspects positive and negative impacts. Zoo has also the
same, on one hand there are so many positive things for them but negatively
for some animals have provided small area for their movement. The love
birds who are 35 in numbers, which are said to be very sensitive, are also in
a very good condition in the zoo. It means that the birds are comfortable in
the zoo
[17, 18]
. The males always have to impress the females for mating.
This proves that the birds in the zoo are free to crossbreed too
[19]
.

Positively to safe from very cold in winter season the Alav or sigri (Hot
fire Pot) has been provided to Royal Bengal and White tigers. In summer
season the sprinkler fountain has been provided to cool in the enclosure of
spotted deer, black buck and sambar, monkey cages, bird’s cages, sloth bear
cage, white and royal Bengal tiger enclosure. Monday is the weekly closure
day of the Maitri baag zoo, and on this day fast for the animals. Each report
of the animals i.e. their death, disease, food, etc. is given to the head office

116. Page | 111
of Delhi time to time. The animals are in a good condition and even it was
known by that one white tiger is 21 years old and it sustain with good health
while the common age of tigers are 16-18 years
[20]
. Chhattisgarh White tiger
'Kishan' dies of cancer at Maitri baag zoo in Bhilai reported in The Times of
India, this story is covered from September 1, 2022.
Conclusion
The Maitri baag zoo is very helpful for a lot in the conservation of
animals and birds. In zoo proper cleaning of their cages on regular basis to
keep them disease free and given to the animals Albendazole per month for
de-worming. There are many zoos which harm the animals and birds to teach
some activities but the survey of Maitri baag zoo that the birds kept here are
comfortable and are not harmed. The birds and the animals are kept together
in pairs for their proper breeding cycle. Their young ones after growing into
adult are left in the forest for their improvement. It is a good place where a
researcher can observe all the activities and the characters of the birds. The
conclusion is that from the observation that zoos are the special places where
the birds and animals can be saved by providing them natural environment
and their protection can be done.
References
1. Annual Report Maitri Baug zoo 1718.pdf (Accessed on 30.3.23)
2. https://en.wikipedia.org/wiki/Maitri_Bagh#References (Accessed on
30.3.23)
3. https://durg.gov.in/tourist-place/maitri-bagh (Accessed on 30.3.23)
4. Namrata Deshmukh, Shweta Sao and RK Singh. Exploring the fauna of
Maitri Garden, Bhilai, Chhattisgarh, India, International Research
Journal of Biological Sciences. 2016;5(11):36-39.
5. Michael Roberts R. National Research Council. Animal Care and
Management at the National Zoo: Final Report. Washington, DC: The
National Academies Press, 2005. Doi: 10.17226/11212.
6. Blunt Wilfrid. The Ark in the Park: The Zoo in the Nineteenth Century.
Hamish Hamilton, London, 1976. ISBN 0- 241-89331-3
7. https://www.twinkl.co.in/teaching-wiki/white-tiger (Accessed on
10.4.23)
8. Braverman Irus. Zooland: The Institution of Captivity. Stanford
University Press, Stanford, 2012. ISBN9780804783576.

117. Page | 112
9. Hyson Jeffrey. Jungle of Eden: The Design of American Zoos.
Environmentalism in Landscape Architecture, Conan, Michel (ed.),
Dumbarton Oaks, Washington, 2000. ISBN 0-88402-278-1
10. Dolly Thakur, Shweta Sao, Singh RK. Exploring the birds of Maitri
Garden, Bhilai, Chhattisgarh, India International Research Journal of
Biological Sciences. 2016;5(11):40-43.
11. Maple T. Toward a Responsible Zoo Agenda. Ethics on the Ark: Zoos,
Animal Welfare and Wildlife Conservation, Smithsonian Institution
Press, Washington, 1995. ISBN 1-56098-515.
12. ZSI. Zoological Survey of India-History and Progress 1916-1990.
Zoological Survey of India, Published by ZSI, Kolkata, 1990, 109.
13. Perrins and Christopher (1988). Obituary: Salim Moizuddin Abdul Ali.
Ibis: Journal of the British Ornithologists' Union, 130(2), 305-306, Doi:
10.1111/j.1474- 919X.1988.tb00986.x.
14. Chan S, Crosby MJ, Islam MZ, Tordoff AW. Important Bird Areas in
Asia: Key Sites for Conservation. Bird Life International, 2004, 2.
ISBN-13: 978- 0946888542
15. https://www.google.com/search?q=animal+mortality&oq=&aqs=chrom
e.1.69i59i450l8.1296950249j0j15&sourceid=chrome&ie=UTF-8
(Accessed on 11.4.23)
16. https://timesofindia.indiatimes.com/city/raipur/white-tiger-kishan-dies-
of-cancer-at-maitri-baag-zoo-in-bhilai/articleshow/93915711.cms
(Accessed on 12.4.23)
17. Lever C. Naturalised Birds of the World. London, United Kingdom: T
& A D Poyser, 2005, 24-26. ISBN 978-0- 7136-7006-6.
18. Desai JH, Malhotra AK. Annual gonadal cycle of Black Kite Milvus
Migrans Govinda. Journal of the Yamashina Institute for Ornithology.
1982;14(2-3):143-150. Doi:10.3312/jyio1952.14.143.
19. Véronique Sanson. Gardens and Parks of Singapore. Oxford University
Press, 1992. ISBN978- 0-19-588588-0
20. https://www.google.com/search?q=tatal+white+tiger+population&oq=ta
tal+white+tiger+population&aqs=chrome..69i57j0i13i512j0i22i30.1927
8j0j15&sourceid=chrome&ie=UTF-8 (Accessed on 12.4.23)

118. Page | 113
Chapter - 8
Succession of Cable Bacteria and Its
Biogeochemical Impact in Marine Sediments



Authors
Apoorva D
Department of Microbiology, Maharanis Science College for
Women, Maharani Cluster University, Bengaluru, Karnataka,
India
Vishwanatha T*
Department of Microbiology, Maharanis Science College for
Women, Maharani Cluster University, Bengaluru, Karnataka,
India
Keshavamurthy M
Department of Life Sciences, Acharya Bangalore B-School,
Bengaluru, Karnataka, India

119. Page | 114

120. Page | 115

Chapter - 8
Succession of Cable Bacteria and Its Biogeochemical Impact
in Marine Sediments
Apoorva D, Vishwanatha T* and Keshavamurthy M



Abstract
In the recent decade a new class of multicellular organisms known as
"cable bacteria" was found to be capable of producing and resolving electrical
currents over centimeter-scale distances. Cable bacteria are multicellular
filamentous bacteria belonging to the family, Desulfobulbaceae whose long-
distance electron transport (LDET) couples the oxidation of sulphide to the
reduction of oxygen over centimeter distances. No freshwater or marine cable
bacteria species have so far been isolated and cultured in pure form. In
sediments covered by anoxic and sulfidic bottom water, cable bacteria were
largely missing, highlighting their need on oxygen or nitrate as electron
acceptors. Cable bacterial populations were low at places that underwent brief
reoxygenation. Their population in sites with seasonal hypoxia correlated
linearly with sulphur supply. Can capture electron suppliers and electron
acceptors that are widely separated in space by carrying electrons from cell to
cell, giving them a competitive advantage for surviving in aquatic sediments.
A new sort of electrical cooperation between cells is required by the
underlying process of long-distance electron transport, which questions
several long-held beliefs about the energy metabolism of multicellular animals.
The present understanding of these fascinating multicellular bacteria is
summarized in this chapter.
Keywords: Cable bacteria, electron transport, biogeochemical impact,
succession, electric currents
Introduction
Cable bacteria are multicellular, filamentous bacteria found worldwide in
marine and freshwater sediments. They are motile and actively positioned
themselves in an oxygen-sulfide gradient, presumably by chemotaxis (Cable
bacteria genomes do not contain flagella genes, but instead several
polysaccharide exporters, which could be involved in excretion-based gliding

121. Page | 116
motility)
[1, 2, 3, 4]
. Cable bacteria are multicellular filamentous bacteria that are
found throughout the world and are electrically conductive; they move
electrons from oxygen reduction at one end to sulphide oxidation at the other
end over centimeter lengths
[4]
. Thus, unlike any other known creature, cable
bacteria divide their main, energy-saving redox process into two smaller
reactions that take place in cells that may be several centimeters apart from
one another. The cable bacteria live in anaerobic places like tidal pools, mud
flats and salt marshes. They are adapted to neutral pH. The bacteria may
connect to each other, forming extremely dense networks of living electricity.
It was seen that these biocables can sustain an electric current that's
comparable to the current density in copper wiring that we use in our everyday
lives
[5]
.
The bacterium was first discovered in 2010 by microbiologist Lars Peter
Nielsen of Aarhus University in Denmark, who was studying the mud on the
sea floor of the city's port. The mud was coursing with detectable levels of
electricity. At the time, he and his colleagues suspected that the electric
currents might be attributable to some sort of external transport network
between individual bacteria or other microscopic organisms. Later the truth
was described that "our experiments showed that the electric connections in
the seabed must be solid structures built by bacteria” by the lead author of
paper published in Nature in 2012, Christian Pfeffer in the press release
[6,7]
.
Structure of cable bacteria
Cable bacteria are small, fragile - one hundred times thinner than a human
hair, made up to 10,000 cells each about microns across, all stacked on top of
each other to form a long, thin strand. It consists of long, unbranched sets of
cells, which are vertically oriented in the sediments. Cells within a cable are
interconnected at the cell- junctions, and a series of ridges are present across
the length of the filaments
[8]
. Owing to their motile nature, cable bacteria align
themselves along vertical redox gradients present in the water-sediment
interface. Under microscope, the bacteria look a bit like the cables used in
electric devices. Inside each bacterium, 15-17 distinct fibers run lengthwise,
each capable of conducting electricity. The long fibres are made up of many
connected cells, each only a micrometer long
[8, 9]
.

122. Page | 117

A B
Fig 1: A) Microscopy image of a cable bacterium; B) Scanning electron microscopy
image of a cable bacterium cell
Source: https://asm.org/Articles/2022/July/Cable-Bacteria-Electric-Marvels-of-the-
Microbial-W
Classification of cable bacteria
Phylogenetically, cable bacteria belong to the deltaproteobacterial family
Desulfobulbaceae, which otherwise is known to contain sulfate-reducing or
sulfur-disproportionating species but not canonical, aerobic sulfide oxidizers.
Based on 16S rRNA gene sequence phylogeny, cable bacteria form a
monophyletic sister group to the genus Desulfobulbus. Currently, the cable
bacteria clade consists of the genera “Candidatus Electrothrix”, a marine cable
bacteria and “Candidatus Electronema", a fresh water form, with 6 described
candidate species; so far, none of them has been isolated into pure culture
[1,10]
.
Although the organism have tentatively been taxonomically placed in an
existing bacteria family by sequencing of 16S rRNA genes and fluorescence
in situ hybridization (FISH) analysis, the researchers say they are radically
different from any other bacteria they have found so far. And it share only 92%
of their DNA with any other species in the family. By this Nielsen told Ed
Yong “They’re so different that they should probably be considered a new
genus" at Discover's Not Exactly Rocket Science
[3, 12, 13]
.
First experimental proof for the existence of cable bacteria
In a redox reaction oxidizers gain electrons, while reducers lose electrons.
During that exchange, electrons can also be freed up to use as energy. In cable
bacteria the following reaction occurs, H2S (hydrogen sulfide) + 2O2 ->
SO4^-2 (sulfate) + 2H^+. But for this to occur they need oxidizer to take those
electrons, like oxygen. But the soil in which they were found was anoxic and
hydrogen sulfide rich. In the experiment, containing this sample of soil with
cable bacteria in a beaker, the hydrogen sulfide was disappearing as the time

123. Page | 118
passed due to cable bacteria. One way to get there is through the process of
diffusion, where oxygen molecules soak into the sediment from the water
above it. But diffusion is slow and couldn't account for the speed at which the
hydrogen sulfide seemed to be disappearing in this experiment. Another
option was that small, burrowing animals were helping to move oxygen
directly to the sulfide, except, the researchers had removed all of those before
starting their experiment. These results proved the existence of multicellular
cable bacteria.
[14, 15]
.
Metabolism
The bacteria behave like electrical cables, capable of conducting
electricity over a distance of several centimeters, a far greater span than
scientists had previously imagined. They are electrically conductive by
transferring electrons from sulfide oxidation at one end over centimeter
distances to oxygen reduction at the other end i.e., they facilitate long distance
electron transport (LDET) over centimeter distance, thereby coupling the
oxidation of sulphide (H2S) in deeper sediment layers with the reduction of O2
or nitrate near the sediment-water interface, thereby generating a 1 - 4 cm deep
suboxic zone devoid of O2 and H2S. Unlike any other organism known, cable
bacteria thus split their central energy-conserving redox reaction into two half-
reactions that occurs in different cells as far as several centimeters apart. It
shuttles the electrons along its cells so that the reaction can take place. In the
process, that produces enough energy for the entire bacterium. This type of
metabolic behavior certainly does not conform to the longstanding dogma in
biology that every individual living cell independently generates its own
energy supply
[16, 17]
.
The spatial separation of the redox half reactions results in a characteristic
pH profile: a pH maximum by proton consumption in the oxic zone and a pH
minimum by sulfide oxidation in the sulfidic zone. Cable bacteria are able to
perform this amazing feat using a series of parallel fibers, sandwiched between
the cell membrane and the cell envelope. These fibers not only transport
electrons but also help connect the bacteria's cells together, allowing them to
form their distinct strands. And this electron transportation is remarkably
efficient too. With support from metaproteomics of a Ca. Electronema
enrichment, the genomes suggest that cable bacteria oxidize sulfide by
reversing the canonical sulfate reduction pathway and fix CO2 using the
Wood-Ljungdahl pathway. Cable bacteria show limited organotrophic
potential, may assimilate smaller organic acids and alcohols, fix N2 and
synthesize polyphosphates and polyglucose as storage compounds; several of
these traits were confirmed by cell-level experimental analyses
[18, 19, 20]
.

124. Page | 119

Fig 2: Genome-based metabolic model for cable bacteria with emphasis on electron
flow and energy conservation during oxygen and nitrate-dependent sulfide oxidation
(Kjeldsen et al., 2019)
Mechanism: How LDET (long distance electron transport chain) occurs?
After oxidation, electrons are channelled into the periplasm, where they
are transferred by cytochromes onto conductive filaments containing e-pili
(electrically conductive pili), which are composed of aromatic amino acids
and enable LDET. After LDET occurs, the electrons are offloaded directly to
final electron acceptors like oxygen and nitrate. An interesting feature in this
metabolic pathway is that energy conservation occurs only in the sulfide-
oxidizing cells present in the anoxic sediment, and not in the oxygen-reducing
cells. The phenomenon of mining sulfides deeper in the sediment and
transporting the electrons to reduce oxygen provides a competitive advantage
to cable bacteria, as they can utilize the redox gradients to outperform other
local sulfur oxidizing bacteria
[21, 22]
.

125. Page | 120
Techniques: Including scanning transmission electron microscopy–
energy-dispersive X-ray spectroscopy (STEM-EDX), confocal Raman
microscopy and stable isotope labelling, have further revealed that the
periplasmic wires of cable bacteria possess a conductive protein core that
relies on nickel as a coenzyme. The fibres are composed of a nickel-rich
protein core (just 27% of their cross-sectional area), the core proteins contain
a sulfur-ligated nickel cofactor that channels the electric current. The outer
layer is composed of a nickel-deficient insulating protein shell. In this respect,
their cross-sectional structure resembles that of standard household electrical
wires
[23, 24, 25]
.
The researchers further demonstrated the role of nickel in their conduction
by oxidizing or selectively removing it from certain samples. When they did
so, the conductivity of the fibres dramatically decreased. Their results extend
the known length scale of protein conduction from micrometers to centimeters.
LDET along living, individual cable bacteria filaments has recently been
demonstrated using resonance Raman microscopy; other metabolic traits have
only been indirectly inferred from the disappearance of substrates or the
appearance of metabolites in the sediment environment
[26]
. A consistent
model for cable bacteria metabolism and intra- and intercellular electron
transport is currently lacking, and the evolutionary origin of this unique
lifestyle remains unclear. Likewise, neither the mechanism of LDET nor the
underlying biological structures have been identified; the best candidates are
continuous periplasmic fibers of unknown composition that run along the
entire filament length and show charge storage capacity
[27]
.
Conductivity in cable bacteria
The cables have extremely high conductivity, and they rival state-of-the-
art polymers that we have developed for things like foldable cell phones and
solar panels. The electrical conductivity of the bacteria couldn't be measured
directly, by its small and fragile nature but by several types of indirect
evidence they have proved this. Electron transport within living cells is
essential for energy conservation in all respiring and photosynthetic organisms.
While a few bacteria transport electrons over micrometer distances to their
surroundings, filaments of cable bacteria are hypothesized to conduct electric
currents over centimeter distances
[28]
. Resonance Raman microscopy was
used to analyze cytochrome redox states in living cable bacteria. Cable-
bacteria filaments were placed in microscope chambers with sulfide as
electron source and oxygen as electron sink at opposite ends. Along individual
filaments a gradient in cytochrome redox potential was detected, which
immediately broke down upon removal of oxygen or laser cutting of the

126. Page | 121
filaments. Without access to oxygen, a rapid shift toward more reduced
cytochromes was observed, as electrons were no longer drained from the
filament but accumulated in the cellular cytochromes. These results provide
direct evidence for long-distance electron transport in living multicellular
bacteria
[29, 30]
.
Long-distance electron transport by cable bacteria is supported by several
observations:
i) Changes in oxygen availability in the water column have an
immediate effect on sulfide oxidation several centimeters into the
sediment, which is faster than what can be explained by diffusion.
ii) Electron transport occurs even where cable bacteria span a
nonconductive barrier in the sediment like an inserted glass bead
layer or a filter with pore size 22 µm.
iii) A wire cutting through the suboxic zone rapidly disrupts conduction.
However, direct demonstration of electric conductance by individual
cable-bacteria filaments is still lacking
[31]
.
How cable bacteria have evolved?
The high number of conserved Desulfobulbaceae genes as well as unique
cable bacteria genes, together with an average Desulfobulbaceae genome size,
suggests that the divergence of the cable bacteria clade and the evolution of
the unique filamentous “electrogenic lifestyle” of its members were driven by
neither massive gene loss nor major genome expansion
[32]
. Rather, substantial
horizontal gene transfer in combination with the moderate replacement and
divergence of ancestral genes was key for the evolution of cable bacteria. This
could imply that electric conduction along filaments may also have evolved in
other phylogenetic lineages, as indicated by putative LDET in a filamentous
groundwater Desulfobulbaceae species distinct from the Ca.
Electrothrix/Electronema clade, or the possibly electric signal transduction in
the filamentous cyanobacterium Phormidium uncinatum
[33, 34]
.
Why the bacteria have evolved like this?
It is seen that just a few centimeters below the sea floor there is a rich,
largely untapped energy source: negatively charged sulfur atoms called
sulfides. The surrounding mud is largely devoid of oxygen by which most
organisms are unable to harvest the energy from these chemicals. For
respiration (energy-harvesting equation) organisms need oxygen to accept the
spare electrons from the energy rich, electron donor sulfide food source. But
it’s analogous to need to both eat food (the sulfide) and breathe air (the oxygen)

127. Page | 122
in order to survive. The bacteria solve this problem by traversing the distance
between their food and their oxygen source with a circuit capable of carrying
electrons. At the bottom end, the organism harvests energy from the sulfides,
then sends the electrons upward. At the top, near the oxygen-rich sea water, it
is able to use the abundant oxygen available to conduct respiration. As a result,
the bacteria have only been found so far in anaerobic sea floor sediments
[35,
36]
.

Fig 3: A) Electrogenic sulfur oxidation in aquatic sediments by cable bacteria. B)
Phylogeny of the Desulfobulbaceae inferred by maximum likelihood analysis based
on the concatenated amino acid sequence (Kjeldsen et al., 2019).
Genome of cable bacteria
The morphologically and metabolically distinct cable bacteria still largely
feature the core genomic makeup of the Desulfobulbaceae, including an
almost complete canonical dissimilatory sulfate reduction (DSR) pathway.
Only 25 of the 806 core gene families of the Desulfobulbaceae were not
detected in any of the cable bacteria genomes. Core gene families missing in
cable bacteria include gene families that encode flagella, the glycolytic
enzyme enolase, subunits DsrOP of the DsrKMJOP complex (44), and the
original NADH-quinone oxidoreductase (Nuo) enzyme complex, which has
apparently been replaced with a xenolog by lateral gene transfer
[37, 38]
.
A comparison of the cable bacteria genomes versus other
Desulfobulbaceae using the Clusters of Orthologous Groups (COG) revealed
that the functional categories “energy production and conversion,” “amino
acid transport and metabolism” and “carbohydrate transport and metabolism”
were underrepresented in cable bacteria genomes. This is a first indication of
a limited organotrophic catabolic potential. Furthermore, and consistent with
their unique lifestyle, a large fraction (37 to 66%) of cable bacteria genes could

128. Page | 123
not be assigned to a COG category, and many gene families were unique and
not found in other Desulfobulbaceae. In “Ca. E. aarhusiensis MCF,” a total of
1,721 gene families, representing approximately 44% of its total gene families,
were not present in other Desulfobulbaceae or highly divergent from their
homologs. Of these, 385 were also detected in at least one of the other, more
incomplete Ca. Electrothrix genomes. Across t he Ca.
Electrothrix/Electronema genus boundary, 197 gene families (representing
212 individual genes) were unique and conserved for the cable bacteria lineage.
Last common ancestor (LCA) analysis predicted that approximately half of
these cable bacteria-specific genes originated from Deltaproteobacteria
(21.7%) or Gammaproteobacteria (28.8%), including many from the sulfur-
oxidizing orders Chromatiales and Thiotrichales (45-47)
[39, 40]
. Approximately
20% of the cable bacteria-specific genes could not be assigned to an ancestral
lineage, indicating an origin from a genomically undescribed donor lineage or
that they arose from evolutionary innovation. The functional role of these
cable bacteria-specific gene families could not be determined, as almost half
of them encode hypothetical proteins and 71% could not be assigned a COG
category. Remarkably, however, approximately one third of them has a
predicted extracytoplasmic or membrane localization, suggesting major
innovations in the cell envelope, which is consistent with the conspicuous
ultrastructure of the cable bacterium cell envelope (43)
[41]
.
Significance
Scientists think that these interconnected mats of complex
microorganisms could be involved in the regulation of earth's soil and ocean
biogeochemistry. This is important phenomenon because it provides a model
for life in other places with no other things for living things, like other planets.
This lets us guess not only about life out in space, but about the origin of life
on earth too
[42, 43]
.
 Cable bacteria were found to be associated with the roots of aquatic
plants, such as the rice plant (Oryza sativa). This plant-cable bacteria
relationship could mitigate sulfide toxicity in rice plants and seagrass
meadows.
 Cable bacteria are also important players in biogeochemical cycling,
as they may acidify their immediate surroundings, thereby
mobilizing essential plant nutrients like phosphates and iron.
 Cable bacteria could also potentially help in nitrogen fixation, which
may eventually lead to generation of ammonia and subsequently
improve the nitrogen availability to plants.

129. Page | 124
 In rice-vegetated soils, inoculation of cable bacteria leads to a
significant decrease in methane emissions, since cable bacteria
compete with methanogens for the same substrates.
The metabolic activity of cable bacteria has distinct effects on sediment
biogeochemistry, especially on the cycling of sulfur, iron, phosphorus, and
nitrogen, with implications for eutrophication and habitability of sediments.
Via sulfur cycling, cable bacteria, both in marine and freshwater habitat,
highlights their influence also on the carbon cycle with implications for the
world climate. This importance makes it crucial to study cable bacteria in
depth
Applications
Since much is left to be understood about several fundamental aspects of
cable bacteria, relatively few applications have been conceived. However,
even a cursory glance at these fascinating microbes is sufficient to conclude
that they will likely have several useful applications in the future
[44,45]
.This
discovery has some major potential for future technology, For example:
 We could one day grow living electrical wires in the lab, something
that could help get us closer to making biodegradable electronics. We
can use agar pillar to grow cable bacteria, especially fresh water cable
bacteria by gradient columns.
 Direct current and alternating current signals were successfully
shown to pass through the conductive filaments of cable bacteria.
Interestingly, cable bacteria were also demonstrated to work as
transistors, making them relevant in designing computational circuits.
 We could also use these bacteria in medical implants that could work
for a certain period of time and then just get broken down by the
human body and disappear when the patient is better.
Overview
Cable bacteria, even though, at first glance, their genomes resemble
sulfate-reducing Desulfobulbaceae, are chemolithoautotrophs and mixotrophs
that oxidize sulfide by reversing the canonical sulfate reduction pathway.
Electrons are channeled via the quinone pool into the periplasm, where
cytochromes transfer them onto conductive fibers that contain e-pili. After
LDET over centimeter distances, electrons are transferred directly from the
periplasmic fibers to the terminal electron acceptors oxygen, nitrate, and
nitrite, which are reduced by periplasmic enzymes, apparently without further
energy conservation
[46]
. This model implies that energy conservation occurs

130. Page | 125
only in the anodic, sulfide-oxidizing cells, both by substrate-level and
oxidative phosphorylation. In contrast, the cathodic, oxygen-or nitrate-
reducing cells would have no means of energy conservation but merely act as
electron sink for the entire cable bacterium filament. A first indication for this
unusual division of labor is provided by visualizing active protein biosynthesis
in marine cable bacteria from oxic, suboxic, and sulfidic sediment layers by
bioorthogonal noncanonical amino acid tagging (BONCAT) (49). In
agreement with the proposed energy distribution, >90% of cable bacteria cells
detected in the suboxic and sulfidic layers were actively synthesizing new
protein, whereas protein biosynthesis in the oxic surface cells could be
detected in only very few filaments, accounting for approximately 20% of oxic
cable bacteria cells
[47, 48]
.
The cable bacteria’s evolutionary descent from obligate anaerobic sulfate
reducers implies that a lack of energy conservation is not their only challenge
in the oxic zone: oxygen likely is inhibitory to many of their core enzymatic
systems, high oxygen reduction rates inevitably generate abundant reactive
oxygen species, and the high pH may inhibit and denature periplasmic and
outer membrane proteins. Yet, for the multicellular cable bacterium, the lack
of growth and a high death risk for the cells in the oxic zone may constitute
an affordable price for access to a potent electron sink and the monopolization
of sulfide oxidation. The chemotaxis of cable bacteria and their ability to move
in loops (48) allows each filament to direct a few cells at a time to the oxic
zone to fulfill their essential cathodic function, i.e., flaring off electrons by
reducing oxygen. While exposed to oxygen, these cells may live on their
storage compounds (polyphosphate and polyglucose) that have been
accumulated and can be recharged during periods in the anoxic zone
[49, 50]
.
Conclusion
Cable bacteria filaments assume different biogeochemical and
physiological roles that are reminiscent of functional specialization within an
organism that is well adapted to its sedimentary habitat. Cable bacteria behave
like multicelled organisms that respond to chemical and physical stimuli in a
highly differentiated manner. Their complex lifestyle is likely connected to
uncharacterized genes that may encode novel means of cell–cell
communication and differential gene expression. Cable bacteria can affect
sulfide concentration below a depth of 15 mm within minutes in response to
changes in oxygen supply at the sediment surface. The speed of this response
implies an absence of differentiation between the cable bacterial cells
positioned in the oxic versus suboxic zones (i.e., between cells operating
cathodically versus anodically). An additional change in sulfide concentration

131. Page | 126
at depth on the scale of hours, indicating a behavioral or regulatory response
of cable bacteria to changes in oxygen supply at the sediment surface. These
bacteria are capable of withstanding rapid changes in the availability of their
electron acceptor (oxygen) and identifying that they may be capable of
modulating their electron harvesting capacity based on the availability of
oxygen.
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