Chemical engineering- STUDY ORIENTED PROJECT

This is a ppt for my study-oriented project in chemical engineering focusing on the study of chemical pre-treatment methods for the extraction of cellulose and lignin from biomass

1. STUDY ORIENTED PROJECT STUDY OF CHEMICAL PRETREATMENT METHODS FOR EXTRACTION OF CELLULOSE AND LIGNIN FROM BIOMASS BY MUSKAN CHANDAK – 2022A1PS1481G

2. CONTENTS 1. INTRODUCTION BIOMASS(ITS COMPOSITION AND SOURCES) PRETREATMENT NEED AND METHODS 2. LITERARY REVIEW 3. CONCLUSION 4. REFERENCES

3. Introduction: Biomass: Biomass is a renewable organic material that comes from plants and animals. Biomass can be burned directly for heat or converted to liquid and gaseous fuels through various processes. Lignocellulose: It refers to plant dry matter (biomass). It comprises two carbohydrate polymers, cellulose and hemicellulose, and an aromatic-rich polymer called lignin. Any biomass rich in cellulose, hemicelluloses, and lignin is commonly called lignocellulosic biomass. It can be used as raw material to produce biofuels. Composition of biomass:- Cellulose: It is an organic compound with the formula (C 6 H 10 O 5 ) n . It is a polysaccharide and is derived exclusively from glucose. It p rovides structural support to plant cell walls and serves as a major source of dietary fibre for many organisms. It is used in paper, textiles, adsorbent, food, and other industries. The cellulose content of cotton fibre is 90%, wood is 40–50%, and dried hemp is approximately 57%. Lignin: It is a complex organic polymer that forms crucial structural materials in the support tissues of most plants. Lignin is essential for forming cell walls, especially in wood and bark, because it lends rigidity and doesn't rot easily. Chemically, lignin is a polymer made by cross-linking phenolic precursors. Lignin is mainly used for fuel and has many valuable applications, like nanoparticle synthesis, supercapacitor electrodes, and photocatalysts. Hemicellulose: It is a heteropolymer (matrix polysaccharides) present along with cellulose in almost all terrestrial plant cell walls. It is branched, shorter in length than cellulose, and tends to crystallise . It can be hydrolysed by dilute acid or base and many hemicellulase enzymes. Significant examples include xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan. It is composed of diverse sugars, including the five-carbon sugars xylose and arabinose, the six-carbon sugars glucose, mannose and galactose, and the six-carbon deoxy sugar rhamnose. It is mainly used in biofuels and bioproducts.

4. SOURCES OF BIOMASS Agricultural crops and residue, forestry crops and residue, Industrial residue, animal residue, municipal solid waste and sewage are biomass sources. Agricultural residues are indeed one of the preferred sources of biomass for several reasons: Renewable: Since they are derived from crops, agricultural residues can be replenished each growing season, fossil fuels Abundance: Agricultural residues are readily available in large quantities because they are generated from various farming activities. This makes them a consistent and abundant source of biomass. Low Cost: Agricultural residues are considered waste or by-products of existing agricultural practices and can be acquired at low or no cost. Reduced Environmental Impact: Utilizing agricultural residues for biomass reduces environmental impact by preventing the release of greenhouse gases through burning or decomposition, effectively managing waste while producing useful energy or products.

5. Agricultural waste and their composition: Need for pretreatment: Cellulose fibres are cross-linked to the matrix of lignin and hemicelluloses, forming a complex recalcitrant structure, thereby limiting the extraction/saccharification efficiency of lignocellulosic biomass. The recalcitrant structure is disrupted by the pretreatment process, which increases the accessibility of enzymes to cellulose. The components of lignocellulosic biomass can be easily isolated and used later. Pretreatment increases the efficiency and yield of the extraction process .

6. TYPES OF PRETREATMENT METHODS Pretreatment methods are classified into physical, chemical, physiological and biological Under this study-oriented project, only chemical pretreatment methods have been reviewed for the extraction of cellulose and lignin from biomass .

7. LITERARY REVIEW TYPE OF BIOMASS EXTRACTION METHOD OPERATING CONDITIONS CONCLUSION Banana natural fibre (BNF) Alkali(NaOH) pretreatment followed by bleaching Temperature: Room temperature Time: 3 hour(alkali pretreatment), 2 hour(bleaching) Concentration: NaOH solution of 5,10,15,20 wt % was used for alkali pretreatment. Sodium hypochlorite (20 wt %) was used for bleaching Enrichment of cellulose increases with an increase in the concentration of NaOH. Maximum cellulose enrichment is 88.76%, which occurs after treatment with NaOH (20%) and bleaching using Sodium hypochlorite solution (20%). FTIR analysis shows that well-ordered fibrous matter of untreated BNFs changed into a distorted state that facilitates the removal of hemicellulose, lignin-wax complex, and other impurities. Coastal Bermuda Grass (CBG) Sodium hydroxide pretreatment and enzymatic hydrolysis Temperature:121 °C Time:15 to 90 minutes S: L= 1:10 Concentration: sodium hydroxide solutions of 0.5%,0.75%, 1%, 2%, and 3% (w/v) was used. Optimal conditions for NaOH pretreatment are using 0.75% NaOH for 15 minutes at 121°C. total reducing sugars yield is 71%, and the overall conversion efficiencies for glucan and xylan were 90.43% and 65.11%. 86% of lignin was removed.

8. TYPE OF BIOMASS EXTRACTION METHOD OPERATING CONDITIONS CONCLUSION sugar palm fibres (SPF) delignification and mercerisation which is followed by hydrolysis Temperature: 70 °C (delignification), 21-25°C(mercerisation) Time: 7 hours(delignification), 2hours(mercerisation) 20g SPF is put in 650ml of hot water. Acetic acid(4ml) and sodium chlorite(8ml) was added for delignification resulting in formation of holocellulose which was soaked in 5% w/v NaOH solution (500 ml) for mercerisation. Hydrolysis (60 wt % H2SO4) was used for extracting SPNCCs FTIR results showed that the chemical treatments of delignification (NaClO2) and mercerisation (NaOH) were effectively used to remove lignin and hemicellulose, respectively. SPNCCs were successfully extracted and isolated. Cellulosic content increases after each chemical treatment, changing from 43.88% in the raw sugar palm fibre to 81.5% in the bleached(delignified) fibres and 82.33% in the alkali-treated(mercerised) fibres. Pineapple crown leaf fibre (PCLF) Acid Hydrolysis (Alkali, bleaching treatments were performed at first which was followed rinsing with water to get neutral pH) Temperature: 45 °C Time: 1,2 and 3 hours Concentration: 1M H2SO4 is used for hydrolysis[Initially, alkali and bleaching treatment were done using NaOH (1M) and H 2 O 2 (1M) at 80°C for 1 hour. After hydrolysis, NCC suspension was centrifuged(30 min) at 2000 rpm and ultrasonication(30 min)] NCC obtained after 1,2,3 hour hydrolysis are NCC-1,NCC-2,NCC-3 NCC products had a rod-like particle structure and a strong cellulose crystalline structure typically found in agricultural fibre-based cellulose. NCC-1(NCC obtained after 1 hour hydrolysis) showed highest yield ( 79.37% ) and also was the most thermally stable displaying a higher decomposition temperature(76.98°C) which makes it useful for filler application.

9. TYPE OF BIOMASS EXTACTION METHOD OPERATING CONDITIONS CONCLUSION Sugarcane bagasse and trash Alkali-Peroxide pretreatment(NaOH-H 2 O 2 pretreatment) which was followed by cellulase enzyme hydrolysis Temperature:45-50 °C (enzyme hydrolysis) Time:1 hour(alkali-peroxide pretreatment),48-70 hours (enzyme hydrolysis) pH: 4.8(enzyme hydrolysis),11.5(alkali-peroxide pretreatment) Concentration: Combined H 2 O 2 (3-5%) and NaOH solution(50ml) was added to biomass(2g) to get 4%(m/v) loading. S:L=1:25 Chesson's method shows pretreatment reduces the levels of hemicellulose sugars and lignin. Cellulose content is 48%, 63% after pretreatment with 3%,5% alkali-peroxide. DTG graph shows only 1 major peak(cellulose). Enzyme hydrolysis gives higher reducing sugars and bioethanol yield pine wood sawdust residues Organosolv-based(Levulinic acid) processes for lignocellulose fractionation Temperature:100-210 °C Pressure:100-300kPa Time:6 hours S:L ratio=1:10 (g mL −1 )[pine sawdust was suspended in levulinic acid ] Catalyst: HCl/H 2 SO 4, which reduces the temperature and reaction time needed. The optimum conditions for extracting lignin from pine wood sawdust residues are at 200 °C for 6 hours at 1 atm pressure. 0.1 M HCl is used to the purest lignin(89%) at 140°C,2 hours. 0.01 M H2SO4 is used to extract lignin(79% purity) at 160°C,2 hours. DTG shows maximum degradation at 59 °C due to water removal. Levulinic acid can be easily recycled without compromising its extraction performance and specificity toward lignin.

10. TYPE OF BIOMASS EXTRACTION METHOD OPERATING CONDITIONS CONCLUSION Beech sawdust Solvent thermal treatment Temperature: 170-200 °C, S: L=1/24 Time:25 min(stirring of sawdust and THFA/H20 solvent),2 hour (precipitation of lignin fraction) Concentration: sawdust (2 g) and the THFA/H2O (v/v, 6/4) solvent (24 mL) were stirred, separated, solid residue was washed with 24 ml solvent. The combined filtrate and washing solution was stirred with water(100ml) to precipitate the lignin fraction. After the treatment in THFA/H2O, the powder lignin yield and cellulose pulp yield were 14.5 and 54.4 wt %. Cellulose pulp contained 44.8 wt % cellulose, 2.8 wt % lignin and 6.4 wt % hemicellulose, meaning more than 95% cellulose was retained. The delignification and purity of cellulose were as high as 86.8% and 82.4%. 77.4% pure lignin powder was recovered. XRD patterns confirmed that cellulose was present in raw beech sawdust and cellulose pulp. Nonwood cellulosic biomass (Wheat straw, Pine straw, Alfalfa, Kenaf, and Flax fibre) formic acid treatment followed by peroxy-formic acid treatment (Organosolv treatment) Formic acid treatment: S: L=1:8 (85% organic acid (ratio of formic acid/acetic acid mixture was 70:30 by volume) was added to the biomass), time: 2 hour Peroxyformic acid/peroxyacetic acid (PFA/PAA) treatment: time:2hour, Temperature: 80°C Bleaching(8°C,2 h) was done for complete lignin removal which followed isolation of lignin(105°C) The source of lignin samples was seen to affect the thermal properties. Enthalpy measurements were higher for lignin from flax fibre and alfalfa at 190.57 and 160.90 J/g, respectively. lignin extracted from wheat straw had the greatest thermal stability and highest char yield of 40.41% followed by flax fibre (39.22%), alfalfa (35.04%), and pine straw (29.45%).

11. TYPE OF BIOMASS EXTRACTION METHOD OPERATING CONDITIONS CONCLUSION Wood Meal Deep Eutectic System Temperature:100 ° C,Time : 8.0 hour 0.5 g of wood meal, 19.65 g ChCl and 25.35 g oxalic acid is added into a 250 mL beaker in an oil bath. The reaction was stopped with the addition of ethanol(30ml). All supernatants were combined and the ethanol was removed by rotary evaporation. After precipitation, the supernatant was removed, and the lignin solid was obtained by centrifugation. 5 types of DESys components were used. DESys–4 had the highest lignin extraction because carboxylic acid as the HBD can cleave the β–O–4 linkage in lignin, increasing the extracted amount compared to the DESys with the HBD of alcohols and amides. HBA: HBD =1:2, time=8 h resulted in the highest extraction efficiency. DES requires less energy consumption, and residue can be used for absorption , hence reducing pollution, but with repeated use of DESys, extraction efficiency decreases Lignocellulosic biomass Dissolution using Protic Ionic Liquids Temperature:90 °C Time:24 hours Pressure:1 atmosphere Three PILs [Py][Ac], [Mim][Ac], [Pyrr][Ac] are used to compare their extraction efficiency. ( Conventional ILs are costly, require high temperature (≥100 °C), and have less extraction efficiency. PILs are cheaper, require lesser temperature, have a higher extraction efficiency) PILs can dissolve large amounts of (Kraft) lignin but little to no cellulose, which is necessary for the selective extraction of lignin. Using PILs is effective at modest temperatures(90 °C) and 1 atm pressure. It is inexpensive and gives high extraction efficiency. Ionicity and lignin extraction efficiency increases in the order: [Py][Ac]<[Mim][Ac]<<[Pyrr][Ac]. The greater the difference in pKa , the more the reaction is driven towards the right.

12. TYPE OF BIOMASS EXTRACTION METHOD OPERATING CONDITIONS CONCLUSION Corn Stalk The two-stage pretreatment method resulted in a low lignin- low silica substrate that could be readily digested with low enzyme loadings. Hence, it is used to generate multiple products, including ethanol from bamboo chips. pretreatment by pyrrolidonium ionic liquids followed by enzymatic hydrolysis S: L=1:20 [ Corn stalk (0.25 g) was added into one of the Ionic Liquids (5 g) both with and without deionised water (1 ml) in a 100 ml round-bottomed flask, later stirred in an oil bath] Temperature: 90°C (oil bath) Time: 30 min(oil bath) Precipitates were filtered and dried at 60 °C for 24 h to give the regenerated cellulosic feedstock (RCF). Lignin was also precipitated out. ILs like [ Hnmp ]Cl, [ Hnmp ]CH3SO3, [ Hnmp ]HSO4 and [ Hnmp ]H2PO4 were used. ILs with strong hydrogen bond basicity weaken the hydrogen-bonding network of the polymer chains. Anions of pyrrolidonium -based ionic liquids played a major role in lignin dissolution as the order of [ Hnmp ]Cl > [ Hnmp ]CH 3 SO 3 > [ Hnmp ]HSO 4 > [ Hnmp ]H2PO 3 . [ Hnmp ]Cl and [ Hnmp ]CH3SO3 are the best ionic liquids for lignin regeneration; 85.94% and 56.02% of the original lignin of corn stalk were achieved. IL give a higher yield of RCF and lignin than IL/H 2 O. For reducing sugars, the IL/H2O yield was higher than the IL yield Bamboo chips Alkaline pre-extraction using NaOH and Alkaline Hydrogen Peroxide(AHP) Preatment which was followed by enzymatic hydrolysis Temperature:100 °C (NaOH pre-extraction),75°C (AHP-pretreatment) L: S=10:1 (L/kg) (NaOH pre-extraction) Concentration:4-10% NaOH, 0-6% H 2 O 2 pH:11.5 (was adjusted using NaOH) Time:30-180 min(NaOH pre-extraction), 180 min(AHP-pretreatment) [NaOH pre-extraction was done using a rotating reactor]Experiments were replicated at least thrice .   Alkaline pre-extraction treatment increases the accessibility of bamboo, 96% of cellulose was preserved, and 10% NaOH gave the highest hemicellulose extraction (34.8%). AHP treatment removes lignin. NaOH pre-extraction enhanced delignification in subsequent AHP pretreatment, reducing H 2 O 2 demand to 4% w/w on treated biomass. Two stage pretreatment gives low lignin-low silica substrate which gets easily digested.

13. CONCLUSION Biomass such as those from agricultural residues have abundant cellulose, lignin and hemicellulose. . Isolation and extraction of cellulose and lignin from pretreated biomass offer several advantages. Cellulose, as a renewable and biodegradable polymer, serves as a feedstock for producing biofuels, biomaterials, and chemicals. Lignin, on the other hand, holds potential as a source of aromatic compounds for various industrial applications, including adhesives, coatings, and carbon fibres. However, extraction is difficult due to the complex structure of biomass, which has several cross-linkages between cellulose, lignin and hemicellulose. This reduces the extraction efficiency. To increase the extraction efficiency, it is necessary to overcome the recalcitrance through a combination of chemical and structural changes using chemical pretreatment, which disrupts the complex structure and makes the biomass more accessible to enzymes. This increases the extraction efficiency of lignin and cellulose as we can easily isolate them. Several chemical pretreatment methods have been studied, such as Organosolv-based processes, alkali pretreatment (NaOH), Deep Eutectic Systems, Protic Ionic Liquids, and pyrrolidonium ionic liquids; each demonstrates unique mechanisms and recovery of valuable components, thus contributing to the sustainable utilisation solubilise lignin and disrupt the biomass structure. Organosolv-based processes utilise organic solvents to dissolve the lignin and disrupt biomass structure to efficiently extract cellulose and lignin. Alkali pretreatment (NaOH) Involves the use of sodium hydroxide to break down lignin through a hydrolysis reaction, enhancing the accessibility of cellulose. The deep Eutectic System utilises a eutectic mixture of hydrogen bond donors and acceptors to solubilise lignin and hemicellulose, facilitating biomass fractionation. Protic Ionic Liquids with proton-donating abilities are used to dissolve and depolymerise lignin and cellulose, enabling selective extraction. By enhancing accessibility and reactivity, pretreatment methods enable efficient separation, isolation and extraction of lignin and cellulose from biomass

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16. The end This presentation has been created by Muskan Chandak (2022A1PS1481G) under the supervision of PHD SCHOLAR MILIND JOSHI AND PROF SD MANJARE