green synthesis of metal and their oxide nanoparticles-2.pptx

Title: Green Synthesis of Metal and Metal Oxide Nanoparticles: A Sustainable Approach

Abstract:

In recent years, there has been a growing interest in the green synthesis of nanoparticles, particularly metal and metal oxide nanoparticles, due to their wide range of applications and the increasing need for sustainable production methods. Green synthesis offers an environmentally friendly alternative to traditional chemical synthesis routes by utilizing natural extracts, biomolecules, or other eco-friendly materials as reducing and stabilizing agents. This paper provides an in-depth exploration of green synthesis methods for the production of metal and metal oxide nanoparticles, highlighting their advantages, mechanisms, and applications. Through a comprehensive review of the literature, various green synthesis approaches, including plant-mediated, microbial, and bio-inspired methods, are discussed. The properties and characterization techniques of green-synthesized nanoparticles are also examined, along with their potential applications in catalysis, sensing, drug delivery, and environmental remediation. Overall, this review underscores the importance of green synthesis as a sustainable approach to nanoparticle production and its significant implications for both scientific research and industrial applications.

Keywords: Green synthesis, Metal nanoparticles, Metal oxide nanoparticles, Sustainable production, Catalysis, Sensing, Drug delivery, Environmental remediation.

Introduction
The synthesis of nanoparticles has gained considerable attention in recent years due to their unique physical, chemical, and biological properties, which differ from those of their bulk counterparts. These properties make nanoparticles promising candidates for various applications in fields such as catalysis, electronics, medicine, and environmental remediation. However, traditional methods of nanoparticle synthesis often involve the use of toxic chemicals, high temperatures, and energy-intensive processes, leading to environmental pollution and health hazards. In response to these challenges, there has been a growing interest in developing sustainable and environmentally friendly approaches to nanoparticle synthesis, known as green synthesis.
Green synthesis involves the use of natural extracts, biomolecules, or other eco-friendly materials as reducing and stabilizing agents in nanoparticle synthesis. This approach offers several advantages over conventional synthesis methods, including reduced environmental impact, cost-effectiveness, scalability, and the ability to produce nanoparticles with controlled size, shape, and composition. Among the various types of nanoparticles, metal and metal oxide nanoparticles have received significant attention due to their diverse applications and potential for green synthesis. In this paper, we provide a comprehensive review of green synthesis methods for the production of metal and metal oxide nanoparticles, highlighting their

1. Green synthesis of metal and their oxide nanoparticles Prepared by : Emran Taher Yaseen Muhammad Faieq Rafiq Muhammad Haini Kchill Muhammad Najmadin Hassan Hadi Haji Hussein Midya Sabah Rahman Wareen Abid Sadiq

2. Contents Introduction Biological components Green solvents Stability and toxicity of nanoparticles Mechanism of “green” synthesis for metal and their oxide nanoparticles Conclusion

3. What's green synthesis of nanoparticles?

4.   Biological components for “green” synthesis Innumerable physical and chemical synthesis approaches require high radiation, highly toxic reduct - ants, and stabilizing agents , which can cause pernicious effects to both humans and marine life. In contrast, green synthesis of metallic nanoparticles is a one pot or single step eco-friendly bio-reduction method that requires relatively low energy to initiate the reaction. This reduction method is also cost efficient.  

5. Types of Biological components 1- Bacteria Bacterial species have been widely utilized for com- mercial biotechnological applications such as biore - mediation, genetic engineering, and bioleaching . Bacteria possess the ability to reduce metal ions and are momentous candidates in nanoparticles preparation . For the preparation of metallic and other novel nanoparticles, a variety of bacterial species are utilized. Prokaryotic bacteria and actinomycetes have been broadly employed for synthesizing metal/metal oxide nanoparticles.  Some examples of bacterial strains that have been extensively exploited for the synthesis of bioreduced silver nanoparticles with distinct size/shape morpholo - gies include: Escherichia coli , Lactobacillus casei , Bacillus cereus , Phaeocystis antarctica , Pseu - domonas proteolytica , Bacillus amyloliquefaciens .

6. Types of Biological components 2- Fungi Fungi-mediated biosynthesis of metal/metal oxide nano - particles is also a very efficient process for the genera- tion of monodispersed nanoparticles with well-defined morphologies. They act as better biological agents for the preparation of metal and metal oxide nanoparticles, due to the presence of a variety of intracellular enzyme . Competent fungi can synthesize larger amounts of nano - particles compared to bacteria .   fungi have many merits over other organisms due to the presence of enzymes/proteins/reducing components on their cell surfaces . Many fungal species are used to synthesize metal/metal oxide nanoparticles like silver, gold, titanium dioxide and zinc oxide

7. Types of Biological components 3-Yeast Yeasts are single-celled microorganisms present in eukaryotic cells.Successful synthesis of nanoparticles/ nanomaterials via yeast has been reported by numerous research groups. The biosynthesis of silver and gold nan- oparticles by a silver-tolerant yeast strain and Saccharo - myces cerevisiae broth has been reported .   4- Plants Plants have the potential to accumulate certain amounts of heavy metals in their diverse parts. Consequently, biosynthesis techniques employing plant extracts have gained increased consideration as a simple, efficient, cost effective and feasible methods as well as an excellent alternative means to conventional preparation methods for nanoparticle production. Many researchers have employed green synthesis process for preparation of metal/metal oxide nanoparticles via plant leaf extracts to further explore their various applications

8. Types of Biological components Plants have biomolecules (like carbohydrates, pro- teins , and coenzyme) with exemplary potential to reduce metal salt into nanoparticles. Like other biosynthesis processes, gold and silver metal nanoparticles were first investigated in plant extract-assisted synthesis. Various plants [including aloe vera ( Aloe barbadensis Miller), Oat ( Avena sativa ), alfalfa ( Medicago sativa ), Tulsi ( Osimumsanctum ), , Lemon ( Citrus limon ), Neem ( Azadirachta indica ), Coriander ( Coriandrum sativum ), Mustard ( Brassica juncea ) and lemon grass ( Cymbopogon flexuo - sus )] have been utilized to synthesize silver nanoparticles and gold nanoparticles.

9. Types of Biological components Table :Synthesis of metallic NPs from various biological species Sr. no. Species Nanoparticles Size (nm) Morphology Application Bacteria   Bacillus cereus   Silver   20–40   Spherical   Antibacterial activity Bacteria E. coli DH 5 α Gold 5–50 Hexagonal‑ octahedra --------------------------------- Fungus Rhizopus nigricans Silver 35–40 Round Bactericidal, catalytic Fungus Trichothecium sp. Gold 10-25 Spherical,rod likes and triangle ------------------------------ Yeast MKY3 Silver 2–5 Hexagonal Coatings for solar energy Plants Aloe barbadensis Miller (Aloe vera ) Silver and Gold 10–30 Spherical , triangular Cancer hyperthermia, optical coatings

10. Green solvents Green solvents are environmentally friendly solvents, or biosolvents, which are derived from the processing of agricultural crops .

11. Why green solvents? Low/non- toxicty , thermally stablity , negligible volatility and non-flammable Role of green solvents: The medium of the reaction.

12. Types of green solvents water Ionic Liquid supercritical fluids Deep eutectic solvents

13. Stability and toxicity of nanoparticles The ability to maintain their chemical and p hysical properties over time, without undergoing significant aggregation, precipitation, or transformation over time, extremely in different environmental conditions. Toxicity refer to transformation of nanoparticles that have negative impact on environment. Such as size, shape, and composition.

14. Aggregation and Dispersion Size and Surface Area Environmental Media and Conditions Surface complexation and Colloidal Stability Factor influence stability

15. Aggregation and Dispersion Natural tendency to aggregate due to attractive forces and electrostatic interactions. stability compromised when aggregation occurs, leading to reduce surface area and decrease reactivity. Maintaining dispersion is crucial, especially in applications.

16. The size plays essential role in stability. Smaller nanoparticles tend to have higher surface area. Controlling the particle size is key strategy in enhancing stability. The size of surface area directly impacts the interactions between nanoparticles and surrounding media, this impact stability. Size and Surface Area Environmental Media and Conditions The stability is highly dependent on the nature of the environmental media. Factors such as pH, temperature, and the presence of ions or organic matter influence stability.

17. Surface complexation and Colloidal Stability Surface complexation involves the formation of chemical bonds or interactions on the surface of nanoparticles, impacting colloidal stability. The ability of nanoparticles to remain dispersed as stable colloids in a medium, resisting aggregation or settling.

18. Green synthesis method Silver nanoparticles ( AgNPs ) Such as using tea leaf extraction which is stable in aquatic environment. Sulfurization of AgNPs reduce their toxicity Use biocompatible stabilizing agent like biodegradable polymer and copolymers.

19. Mechanism of “green” synthesis for metal and their oxide nanoparticles Microorganism-based mechanism Plant leaf extract-based mechanism Chemical mechanism

20. Micro organism based-mechanism content Capture of metallic ions synthesis of silver and gold nanoparticle Enzymatic reduction NADH and NADH dependent nitrate

21. Plant leaf extract based mechanism preparation of plant leaf extract parameters ( phytochemical types, concentrations, metal salt concentrations, PH, temperature ) Role of phytochemicals Type of phytochemicals in plant extract ( flavonoids, terpenoids, sugars, amino acids, proteins ) Reduction and stabilization Plant leaf extracts rapidly reduce metal ions and acts as both reducing and stabilizing Composition impact The rate, yield and stability of nanoparticle formation influence by the composition of plant leaf extract with varying concentration of phytochemicals

22. Chemical mechanisms Functional group and FTIR analysis Functional groups in phytochemicals acts as capping and stabilizing nanoparticls . FTIR analysis identifies functional group like –C–O–C–, –C–O–, –C=C–, and –C=O – associated with nanoparticles Capping ligands role Prevent further grouth and agglomeration of nanoparticle