Organosolv pretreatment: an in-depth purview of mechanics of the system

Abstract

The concept of biorefinery has been advancing globally and organosolv pretreatment strategy has seen an upsurge in research due to its efficiency in removing the recalcitrant lignin and dissolution of cellulose. The high-performance organosolv system uses green solvents and its reusability contributes concurrently to the biorefinery sector and sustainability. The major advantage of the current system involves the continuous removal of lignin to enhance cellulose accessibility, thereby easing the later biorefinery steps, which were immensely restricted due to the recalcitrant lignin. The current system process can be further explored and enhanced via the amalgamation of new technologies, which is still a work in progress. Thus, the current review summarizes organosolv pretreatment and the range of solvents used, along with a detailed mechanistic approach that results in efficient pretreatment of LCB. The latest developments for designing high-performance pretreatment systems, their pitfalls, and advanced assessments such as Life Cycle Assessment along with Techno-Economic Assessment have also been deliberated to allow an insight into its diverse potential applicability towards a sustainable future.

Keywords

Lignocellulose biomass / Organic solvent / Pretreatment / Lignin / Cellulose

References

[1] Achinivu EC, Mohan M, Choudhary H, . A predictive toolset for the identification of effective lignocellulosic pretreatment solvents: a case study of solvents tailored for lignin extraction. Green Chem, 2021, 23: 7269-7289.

[2] Agnihotri S, Johnsen IA, Bøe MS, . Ethanol organosolv pretreatment of softwood (Picea abies) and sugarcane bagasse for biofuel and biorefinery applications. Wood Sci Technol, 2015, 49: 881-896.

[3] Aissou M, Chemat-Djenni Z, Yara-Varón E, . Limonene as an agro-chemical building block for the synthesis and extraction of bioactive compounds. Comptes Rendus Chim, 2017, 20: 346-358.

[4] Alio MA, Tugui OC, Vial C, Pons A. Microwave-assisted Organosolv pretreatment of a sawmill mixed feedstock for bioethanol production in a wood biorefinery. Bioresour Technol, 2019, 276: 170-176.

[5] Ambaye TG, Vaccari M, Bonilla-Petriciolet A, . Emerging technologies for biofuel production: a critical review on recent progress, challenges and perspectives. J Environ Manage, 2021, 290: 112627.

[6] Amini N, Dwivedi S, Ahmad W, . Polar solvents enhance the efficiency of microwave pre-treatment of woody biomass. Biomass Bioenergy, 2021, 155: 106281.

[7] Araque E, Parra C, Freer J, . Evaluation of organosolv pretreatment for the conversion of Pinus radiata D. Don to Ethanol Enzyme Microb Technol, 2008, 43: 214-219.

[8] Ashok B, Prasad R, Oinas P, Forssell S. Techno-economic evaluation of a biorefinery to produce γ-valerolactone (GVL), 2-methyltetrahydrofuran (2-MTHF) and 5-hydroxymethylfurfural (5-HMF) from spruce. Renew Energy, 2022, 190: 396-407.

[9] Avelino F, Marques F, Soares AKL, . Microwave-assisted organosolv delignification: a potential eco-designed process for scalable valorization of agroindustrial wastes. Ind Eng Chem Res, 2019, 58: 10698-10706.

[10] Badgujar KC, Bhanage BM. Factors governing dissolution process of lignocellulosic biomass in ionic liquid: current status, overview and challenges. Bioresour Technol, 2015, 178: 2-18.

[11] Balaji C, Banerjee T, Goud VV. COSMO-RS based predictions for the extraction of lignin from lignocellulosic biomass using ionic liquids: effect of cation and anion combination. J Solution Chem, 2012, 41: 1610-1630.

[12] Balan V. Current challenges in commercially producing biofuels from lignocellulosic biomass. ISRN Biotechnol, 2014, 2014: 1-31.

[13] Bär J, Phongpreecha T, Singh SK, . Deconstruction of hybrid poplar to monomeric sugars and aromatics using ethanol organosolv fractionation. Biomass Convers Biorefinery, 2018, 8: 813-824.

[14] Bello S, Ríos C, Feijoo G, Moreira MT. Comparative evaluation of lignocellulosic biorefinery scenarios under a life-cycle assessment approach. Biofuels Bioprod Biorefining, 2018, 12: 1047-1064.

[15] Bensah EC, Mensah M. Chemical pretreatment methods for the production of cellulosic ethanol: technologies and innovations. Int J Chem Eng, 2013, 2013: 719607.

[16] Borand MN, Karaosmanoǧlu F. Effects of organosolv pretreatment conditions for lignocellulosic biomass in biorefinery applications: a review. J Renew Sustain Energy, 2018, 10: 033104.

[17] Brandt A, Hallett JP, Leak DJ, . The effect of the ionic liquid anion in the pretreatment of pine wood chips. Green Chem, 2010, 12: 672-767.

[18] Brandt A, Ray MJ, To TQ, . Ionic liquid pretreatment of lignocellulosic biomass with ionic liquid–water mixtures. Green Chem, 2011, 13: 2489-2499.

[19] Brandt A, Gräsvik J, Hallett JP, Welton T. Deconstruction of lignocellulosic biomass with ionic liquids. Green Chem, 2013, 15: 550-583.

[20] Bulkan G, Ferreira JA, Taherzadeh MJ. Retrofitting analysis of a biorefinery: Integration of 1st and 2nd generation ethanol through organosolv pretreatment of oat husks and fungal cultivation. Bioresour Technol Reports, 2021, 15: 100762.

[21] Castoldi R, Bracht A, de Morais GR, . Biological pretreatment of Eucalyptus grandis sawdust with white-rot fungi: study of degradation patterns and saccharification kinetics. Chem Eng J, 2014, 258: 240-246.

[22] Chaudhari US, Merugu S, Ankathi SK, et al (2022) Combined effects of Ammonia Fiber Expansion (AFEX) pretreatment severity and enzymatic hydrolysis time on microporous structure of corn stover. SSRN Electron J 1–34. https://doi.org/10.2139/ssrn.4034547

[23] Cheng B, Zhang X, Lin Q, . A new approach to recycle oxalic acid during lignocellulose pretreatment for xylose production. Biotechnol Biofuels, 2018, 11: 1-9.

[24] Chin DWK, Lim S, Pang YL, . Effects of organosolv pretreatment using ethylene glycol on degraded empty fruit bunch for delignification and fractionation. IOP Conf Ser Earth Environ Sci, 2020, 463: 7.

[25] Chin DWK, Lim S, Pang YL, Lam MK. Fundamental review of organosolv pretreatment and its challenges in emerging consolidated bioprocessing. Biofuels Bioprod Biorefin, 2020, 14: 808-829.

[26] Chin DWK, Lim S, Pang YL, . Effects of organic solvents on the organosolv pretreatment of degraded empty fruit bunch for fractionation and lignin removal. Sustain, 2021, 13: 1-16.

[27] Chu Q, Tong W, Chen J, . Organosolv pretreatment assisted by carbocation scavenger to mitigate surface barrier effect of lignin for improving biomass saccharification and utilization. Biotechnol Biofuels, 2021, 14: 1-13.

[28] Chum HL, Douglas LJ, Feinberg DA, Schroeder HA (1985) Evaluation of pretreatments of biomass for enzymatic hydrolysis of cellulose. [Organosolv process, wet oxidation, and steam explosion of wood chips] (No. SERI/TR-231-2183). Solar Energy Research Inst., Golden, CO (USA); Colorado State Univ., Fort Collins (USA).

[29] Chum HL, Johnson DK, Black SK. Organosolv pretreatment for enzymatic hydrolysis of poplars. 2. Catalyst effects and the combined severity parameter. Ind Eng Chem Res, 1990, 29: 156-162.

[30] Corsi L, Mateo S, Spaccini F, . Optimization of microwave assisted organosolv pretreatment for enzymatic hydrolysis of cherry tree pruning and pistachio shells. SSRN Electron J, 2022

[31] da Machado A, S, Ferraz A, . Biological pretreatment of sugarcane bagasse with basidiomycetes producing varied patterns of biodegradation. Bioresour Technol, 2017, 225: 17-22.

[32] da Silva ARG, Errico M, Rong BG (2018a) Evaluation of organosolv pretreatment for bioethanol production from lignocellulosic biomass: solvent recycle and process integration. Biomass Convers Biorefin 8:397–411. https://doi.org/10.1007/s13399-017-0292-4

[33] da Silva ARG, Errico M, Rong BG (2018b) Techno-economic analysis of organosolv pretreatment process from lignocellulosic biomass. Clean Technol Environ Policy 20:1401–1412. https://doi.org/10.1007/s10098-017-1389-y

[34] De Santi A, Monti S, Barcaro G, . New mechanistic insights into the lignin β-O-4 linkage acidolysis with ethylene glycol stabilization aided by multilevel computational chemistry. ACS Sustain Chem Eng, 2021, 9: 2388-2399.

[35] De Wild PJ, Huijgen WJJ, Heeres HJ. Pyrolysis of wheat straw-derived organosolv lignin. J Anal Appl Pyrolysis, 2012, 93: 95-103.

[36] del Sánchez-Camargo A, P, Bueno M, Parada-Alfonso F, , . Hansen solubility parameters for selection of green extraction solvents. TrAC Trends Anal Chem, 2019, 118: 227-237.

[37] Dhar P, Vinu R. Understanding lignin depolymerization to phenols via microwave-assisted solvolysis process. J Environ Chem Eng, 2017, 5: 4759-4768.

[38] El Hage R, Brosse N, Sannigrahi P, Ragauskas A. Effects of process severity on the chemical structure of Miscanthus ethanol organosolv lignin. Polym Degrad Stab, 2010, 95: 997-1003.

[39] Fan D, Yang J, Xie X, . Microwave-assisted fractionation of poplar sawdust into high-yield noncondensed lignin and carbohydrates in methanol/p-toluenesulfonic acid. Chem Eng J, 2023, 454: 140237.

[40] Ferreira JA, Taherzadeh MJ. Improving the economy of lignocellulose-based biorefineries with organosolv pretreatment. Bioresour Technol, 2020, 299: 122695.

[41] Gaber MAFM, Knoerzer K, Mansour MP, . Improved canola oil expeller extraction using a pilot-scale continuous flow microwave system for pre-treatment of seeds and flaked seeds. J Food Eng, 2020, 284: 110053.

[42] Gelosia M, Ingles D, Pompili E, . Fractionation of lignocellulosic residues coupling steam explosion and organosolv treatments using green solvent γ-valerolactone. Energies, 2017, 10: 1264.

[43] Goh CS, Tan HT, Lee KT, Brosse N (2011) Evaluation and optimization of organosolv pretreatment using combined severity factors and response surface methodology. Biomass Bioenerg 35:4025–4033. https://doi.org/10.1016/j.biombioe.2011.06.034

[44] Gómez-Cruz I, Romero I, del Contreras M, M, , . Combined extraction and ethanol organosolv fractionation of exhausted olive pomace for bioactive compounds. Adv Sustain Syst, 2022, 6: 2100361.

[45] Gullón P, Gullón B, Dávila I, . Comparative environmental Life Cycle Assessment of integral revalorization of vine shoots from a biorefinery perspective. Sci Total Environ, 2018, 624: 225-240.

[46] Hansen CM. Solubility parameters and introduction. Hansen solubility parameters: a user’s handbook, 2000, Boca Raton: CRC Press.

[47] Hansen CM, Durkee J, Kontogeorgis G, . Hansen solubility parameters, 2007, 2, Boca Raton: CRC Press

[48] Harrison MD, Zhang Z, Shand K, . The combination of plant-expressed cellobiohydrolase and low dosages of cellulases for the hydrolysis of sugar cane bagasse. Biotechnol Biofuels, 2014, 7: 1-14.

[49] Hassanpour M, Abbasabadi M, Gebbie L, . Acid-catalyzed glycerol pretreatment of sugarcane bagasse: understanding the properties of lignin and its effects on enzymatic hydrolysis. ACS Sustain Chem Eng, 2020, 8: 10380-10388.

[50] Hildebrand J, Scott R. The solubility of nanoelectrolytes, 1950, New York: Reinhold.

[51] Hu M, Zhao D, Jin Q, et al (2021) Systematic review and perspective on the progress of algal biofuels. E3S Web Conf 257. https://doi.org/10.1051/e3sconf/202125703008

[52] Isci A, Thieme N, Lamp A, . Production of xylo-oligosaccharides from wheat straw using microwave assisted deep eutectic solvent pretreatment. Ind Crops Prod, 2021, 164: 113393.

[53] Jamaldheen SB, Kurade MB, Basak B, . A review on physico-chemical delignification as a pretreatment of lignocellulosic biomass for enhanced bioconversion. Bioresour Technol, 2022, 346: 126591.

[54] Jang SK, Kim HY, Jeong HS, . Effect of ethanol organosolv pretreatment factors on enzymatic digestibility and ethanol organosolv lignin structure from Liriodendron tulipifera in specific combined severity factors. Renew Energy, 2016, 87: 599-606.

[55] Jeong SY, Lee JW. Optimization of pretreatment condition for ethanol production from oxalic acid pretreated biomass by response surface methodology. Ind Crops Prod, 2016, 79: 1-6.

[56] Jeswani HK, Chilvers A, Azapagic A. Environmental sustainability of biofuels: a review: environmental sustainability of biofuels. Proc R Soc A Math Phys Eng Sci, 2020, 476: 20200351.

[57] Ji H, Lv P. Mechanistic insights into the lignin dissolution behaviors of a recyclable acid hydrotrope, deep eutectic solvent (DES), and ionic liquid (IL). Green Chem, 2020, 22: 1378-1387.

[58] Joy SP, Krishnan C. Modified organosolv pretreatment for improved cellulosic ethanol production from sorghum biomass. Ind Crops Prod, 2022, 177: 114409.

[59] Kabir MM, Rajendran K, Taherzadeh MJ, Sárvári Horváth I. Experimental and economical evaluation of bioconversion of forest residues to biogas using organosolv pretreatment. Bioresour Technol, 2015, 178: 201-208.

[60] Karnaouri A, Asimakopoulou G, Kalogiannis KG, . Efficient production of nutraceuticals and lactic acid from lignocellulosic biomass by combining organosolv fractionation with enzymatic/fermentative routes. Bioresour Technol, 2021, 341: 125846.

[61] Katahira R, Mittal A, McKinney K, . Evaluation of Clean fractionation pretreatment for the production of renewable fuels and chemicals from corn stover. ACS Sustain Chem Eng, 2014, 2: 1364-1376.

[62] Khaw KY, Parat MO, Shaw PN, Falconer JR. Solvent supercritical fluid technologies to extract bioactive compounds from natural sources: a review. Molecules, 2017, 22: 1186.

[63] Kilpeläinen I, Xie H, King A, . Dissolution of wood in ionic liquids. J Agric Food Chem, 2007, 55: 9142-9148.

[64] Kim H-Y, Lee J-W, Jeffries TW, . Effect of oxalic acid pretreatment on yellow poplar (Liriodendron tulipifera) for ethanol production. J Korean Wood Sci Technol, 2009, 37: 397-405.

[65] Klamt A. The COSMO and COSMO-RS solvation models. Wiley Interdiscip Rev Comput Mol Sci, 2017, 8: 1-11.

[66] Kostas ET, Beneroso D, Robinson JP. The application of microwave heating in bioenergy: a review on the microwave pre-treatment and upgrading technologies for biomass. Renew Sustain Energy Rev, 2017, 77: 12-27.

[67] Kumar L, Arantes V, Chandra R, Saddler J. The lignin present in steam pretreated softwood binds enzymes and limits cellulose accessibility. Bioresour Technol, 2012, 103: 201-208.

[68] Kundu C, Lee JW. Optimization conditions for oxalic acid pretreatment of deacetylated yellow poplar for ethanol production. J Ind Eng Chem, 2015, 32: 298-304.

[69] Laure S, Leschinsky M, Fröhling M, . Assessment of an organosolv lignocellulose biorefinery concept based on a material flow analysis of a pilot plant. Cellul Chem Technol, 2014, 48: 793-798.

[70] Lavoie JM, Baré W, Bilodeau M. Depolymerization of steam-treated lignin for the production of green chemicals. Bioresour Technol, 2011, 102: 4917-4920.

[71] Lee KM, Ng KN. Effect of ultrasonication in organosolv pretreatment for enhancement of fermentable sugars recovery from palm oil empty fruit bunches. Prog Energy Environ, 2019, 11: 15-23.

[72] Lee DH, Cho EY, Kim CJ, Kim SB. Pretreatment of waste newspaper using ethylene glycol for bioethanol production. Biotechnol Bioprocess Eng, 2010, 15: 1094-1101.

[73] Lee KM, Zanil MF, Chan KK, . Synergistic ultrasound-assisted organosolv pretreatment of oil palm empty fruit bunches for enhanced enzymatic saccharification: an optimization study using artificial neural networks. Biomass Bioenergy, 2020, 139: 105621.

[74] Li C, Knierim B, Manisseri C, . Comparison of dilute acid and ionic liquid pretreatment of switchgrass: biomass recalcitrance, delignification and enzymatic saccharification. Bioresour Technol, 2010, 101: 4900-4906.

[75] Li MF, Sun SN, Xu F, Sun RC. Baskar C, Baskar S, Dhillon RS. Organosolv fractionation of lignocelluloses for fuels, chemicals and materials: a biorefinery processing perspective. Biomass conversion: the interface of biotechnology, chemistry and materials science, 2012, Berlin, Heidelberg: Springer, 341-379.

[76] Li Q, Gao Y, Wang H, . Comparison of different alkali-based pretreatments of corn stover for improving enzymatic saccharification. Bioresour Technol, 2012, 125: 193-199.

[77] Li SX, Li MF, Bian J, . Biphasic 2-methyltetrahydrofuran/oxalic acid/water pretreatment to enhance cellulose enzymatic hydrolysis and lignin valorization. Bioresour Technol, 2017, 243: 1105-1111.

[78] Li P, He C, Li G, . Biological pretreatment of corn straw for enhancing degradation efficiency and biogas production. Bioengineered, 2020, 11: 251-260.

[79] Liu J, Takada R, Karita S, . Microwave-assisted pretreatment of recalcitrant softwood in aqueous glycerol. Bioresour Technol, 2010, 101: 9355-9360.

[80] Liu F, Dong X, Zhao X, Wang L. Life cycle assessment of organosolv biorefinery designs with the complete use of biomass. Energy Convers Manag, 2021, 246: 114653.

[81] Liu M, Zuo S, Liang Y, . The influence of 3-hydroxy-2-naphthoic acid on agricultural wastes extracted sugar production used as energy sources. Fuel, 2022, 323: 124235.

[82] Lou H, Wang M, Lai H, . Reducing non-productive adsorption of cellulase and enhancing enzymatic hydrolysis of lignocelluloses by noncovalent modification of lignin with lignosulfonate. Bioresour Technol, 2013, 146: 478-484.

[83] Luterbacher JS, Parlange JY, Walker LP. A pore-hindered diffusion and reaction model can help explain the importance of pore size distribution in enzymatic hydrolysis of biomass. Biotechnol Bioeng, 2013, 110: 127-136.

[84] Luterbacher JS, Azarpira A, Motagamwala AH, . Lignin monomer production integrated into the γ-valerolactone sugar platform. Energy Environ Sci, 2015, 8: 2657-2663.

[85] Luterbacher JS, Moran-Mirabal JM, Burkholder EW, Walker LP. Modeling enzymatic hydrolysis of lignocellulosic substrates using fluorescent confocal microscopy II: pretreated biomass. Biotechnol Bioeng, 2015, 112: 32-42.

[86] Majumdar S, Goswami B, Chakraborty A, . Effect of pretreatment with organic solvent on enzymatic digestibility of cauliflower wastes. Prep Biochem Biotechnol, 2019, 49: 935-948.

[87] Mansfield SD, Mooney C, Saddler JN. Substrate and enzyme characteristics that limit cellulose hydrolysis. Biotechnol Prog, 1999, 15: 804-816.

[88] Maurya DP, Singla A, Negi S. An overview of key pretreatment processes for biological conversion of lignocellulosic biomass to bioethanol. 3 Biotech, 2015, 5: 597-609.

[89] McDonough TJ. The chemistry of organosolv delignification. IPST Tech Pap Ser, 1992, 455: 1-17.

[90] McDonough TJ. The chemistry of organosolv delignification. TAPPI J, 1992, 76: 186-193.

[91] Mesa L, López N, Cara C, . Techno-economic evaluation of strategies based on two steps organosolv pretreatment and enzymatic hydrolysis of sugarcane bagasse for ethanol production. Renew Energy, 2016, 86: 270-279.

[92] Mirmohamadsadeghi S, Chen Z, Wan C. Reducing biomass recalcitrance via mild sodium carbonate pretreatment. Bioresour Technol, 2016, 209: 386-390.

[93] Monção M, Hrůzová K, Rova U, . Organosolv fractionation of birch sawdust: establishing a lignin-first biorefinery. Molecules, 2021, 26: 6754.

[94] Montané D, Farriol X, Salvadó J, . Fractionation of wheat straw by steam-explosion pretreatment and alkali delignification. Cellulose pulp and byproducts from hemicellulose and lignin. J Wood Chem Technol, 1998, 18: 171-191.

[95] Moxley G, Gaspar AR, Higgins D, Xu H. Structural changes of corn stover lignin during acid pretreatment. J Ind Microbiol Biotechnol, 2012, 39: 1289-1299.

[96] Nakagame S, Chandra RP, Kadla JF, Saddler JN. Enhancing the enzymatic hydrolysis of lignocellulosic biomass by increasing the carboxylic acid content of the associated lignin. Biotechnol Bioeng, 2011, 108: 538-548.

[97] Novo LP, Curvelo AAS. Hansen solubility parameters: a tool for solvent selection for organosolv delignification. Ind Eng Chem Res, 2019, 58: 14520-14527.

[98] Ofori-Boateng C, Lee KT. Ultrasonic-assisted simultaneous saccharification and fermentation of pretreated oil palm fronds for sustainable bioethanol production. Fuel, 2014, 119: 285-291.

[99] Oliva A, Tan LC, Papirio S, . Effect of methanol-organosolv pretreatment on anaerobic digestion of lignocellulosic materials. Renew Energy, 2021, 169: 1000-1012.

[100] Ong VZ, Wu TY. An application of ultrasonication in lignocellulosic biomass valorisation into bio-energy and bio-based products. Renew Sustain Energy Rev, 2020, 132: 109924.

[101] Paës G, Navarro D, Benoit Y, . Tracking of enzymatic biomass deconstruction by fungal secretomes highlights markers of lignocellulose recalcitrance. Biotechnol Biofuels, 2019, 12: 1-14.

[102] Pathak P, Gupta A, Bhardwaj NK, . Impact of mild and harsh conditions of formic acid-based organosolv pretreatment on biomass fractionation of sugarcane tops. Biomass Convers Biorefin, 2021, 11: 2027-2040.

[103] Pham TLM, Choudhary H, Gauttam R, Singer SW. Revisiting theoretical tools and approaches for the valorization of recalcitrant lignocellulosic biomass to value-added chemicals. Front Energy Res, 2022, 10: 1-18.

[104] Pielhop T, Amgarten J, Von Rohr PR, Studer MH. Steam explosion pretreatment of softwood: the effect of the explosive decompression on enzymatic digestibility. Biotechnol Biofuels, 2016, 9: 1-13.

[105] Potrč S, Čuček L, Martin M, Kravanja Z. Sustainable renewable energy supply networks optimization—the gradual transition to a renewable energy system within the European Union by 2050. Renew Sustain Energy Rev, 2021, 146: 111186.

[106] Prasad A, Sotenko M, Blenkinsopp T, Coles SR. Life cycle assessment of lignocellulosic biomass pretreatment methods in biofuel production. Int J Life Cycle Assess, 2016, 21: 44-50.

[107] Rahikainen JL, Martin-Sampedro R, Heikkinen H, . Inhibitory effect of lignin during cellulose bioconversion: the effect of lignin chemistry on non-productive enzyme adsorption. Bioresour Technol, 2013, 133: 270-278.

[108] Raita M, Denchokepraguy N, Champreda V, Laosiripojana N. Effects of alkaline catalysts on acetone-based organosolv pretreatment of rice straw. 3 Biotech, 2017, 7: 1-10.

[109] Raj T, Chandrasekhar K, Banu R, . Synthesis of γ-valerolactone (GVL) and their applications for lignocellulosic deconstruction for sustainable green biorefineries. Fuel, 2021, 303: 121333.

[110] Ramírez-wong B, Bello-pérez LA, Montaño B. Ionic Liquids and organic solvents for recovering lignin from lignocellulosic biomass. BioResources, 2014, 9: 3660-3687.

[111] Rezania S, Oryani B, Cho J, . Different pretreatment technologies of lignocellulosic biomass for bioethanol production: an overview. Energy, 2020, 199: 117457.

[112] Romaní A, Ruiz HA, Teixeira JA, Domingues L. Valorization of Eucalyptus wood by glycerol-organosolv pretreatment within the biorefinery concept: an integrated and intensified approach. Renew Energy, 2016, 95: 1-9.

[113] Ruiz E, Romero I, Moya M, . Dilute sulfuric acid pretreatment of sunflower stalks for sugar production. Bioresour Technol, 2013, 140: 292-298.

[114] Ryan N, Yaseneva P. A critical review of life cycle assessment studies of woody biomass conversion to sugars. Philos Trans R Soc A Math Phys Eng Sci, 2021, 379: 20200335.

[115] Salapa I, Topakas E, Sidiras D. Simulation and optimization of barley straw organosolv pretreatment. Ind Crops Prod, 2018, 113: 80-88.

[116] Sameni J, Krigstin S, Sain M. Solubility of lignin and acetylated lignin in organic solvents. BioResources, 2017, 12: 1548-1565.

[117] Sar T, Arifa VH, Hilmy MR, . Organosolv pretreatment of oat husk using oxalic acid as an alternative organic acid and its potential applications in biorefinery. Biomass Convers Biorefin, 2022

[118] Schmatz AA, Brienzo M. Butylated hydroxytoluene improves lignin removal by organosolv pretreatment of sugarcane bagasse. Bioenergy Res, 2021, 15: 166-174.

[119] Schmatz AA, Masarin F, Brienzo M. Lignin removal and cellulose digestibility improved by adding antioxidants and surfactants to organosolv pretreatment of sugarcane bagasse. Bioenergy Res, 2022, 15: 1107-1115.

[120] Sheikh MMI, Kim CH, Lee JY, . Production of bioethanol from waste money bills-A new cellulosic material for biofuels. Food Bioprod Process, 2013, 91: 60-65.

[121] Shuai L, Luterbacher J. Organic solvent effects in biomass conversion reactions. Chemsuschem, 2016, 9: 133-155.

[122] Shuai L, Yang Q, Zhu JY, . Comparative study of SPORL and dilute-acid pretreatments of spruce for cellulosic ethanol production. Bioresour Technol, 2010, 101: 3106-3114.

[123] Shuai L, Questell-Santiago YM, Luterbacher JS. A mild biomass pretreatment using γ-valerolactone for concentrated sugar production. Green Chem, 2016, 18: 937-943.

[124] Sillero L, Morales A, Fernández-Marín R, . Life Cycle Assessment of various biorefinery approaches for the valorisation of almond shells. Sustain Prod Consum, 2021, 28: 749-759.

[125] Singh S, Sinha R, Kundu S. Role of organosolv pretreatment on enzymatic hydrolysis of mustard biomass for increased saccharification. Biomass Convers Biorefin, 2021

[126] Singhvi MS, Gokhale DV. Lignocellulosic biomass: hurdles and challenges in its valorization. Appl Microbiol Biotechnol, 2019, 103: 9305-9320.

[127] Sivamani S, Baskar R. Bioconversion of cassava stem to ethanol: oxalic acid pretreatment and co-culture fermentation. Biofuels, 2018, 9: 559-566.

[128] Smit A, Huijgen W. Effective fractionation of lignocellulose in herbaceous biomass and hardwood using a mild acetone organosolv process. Green Chem, 2017, 19: 5505-5514.

[129] Smit AT, Verges M, Schulze P, Lorenz H. Laboratory- to pilot-scale fractionation of lignocellulosic biomass using an acetone organosolv process. ACS Sustain Chem Eng, 2022

[130] Snelders J, Dornez E, Benjelloun-Mlayah B, . Biorefining of wheat straw using an acetic and formic acid based organosolv fractionation process. Bioresour Technol, 2014, 156: 275-282.

[131] Sun W (2021) The feasibility of electro-assisted organosolv pretreatment of lignocellulosic materials for delignification and reducing sugar production Doctoral dissertation, RMIT University).

[132] Sun W, Othman MZ. A selective fractionation method of lignocellulosic materials using electro- assisted organosolv pretreatment. Bioresour Technol, 2019, 288: 121421.

[133] Sun FF, Wang L, Hong J, . The impact of glycerol organosolv pretreatment on the chemistry and enzymatic hydrolyzability of wheat straw. Bioresour Technol, 2015, 187: 354-361.

[134] Sun FF, Zhao X, Hong J, . Industrially relevant hydrolyzability and fermentability of sugarcane bagasse improved effectively by glycerol organosolv pretreatment. Biotechnol Biofuels, 2016, 9: 1-13.

[135] Sun W, Greaves TL, Othman MZ. Electro-assisted pretreatment of lignocellulosic materials in ionic liquid-promoted organic solvents. ACS Sustain Chem Eng, 2020, 8: 18177-18186.

[136] Sun W, Greaves TL, Othman MZ. Effect of inorganic additives and optimisation of the electro-assisted organosolv pretreatment of biomass. J Environ Chem Eng, 2021, 9: 106432.

[137] Sun C, Ren H, Sun F, . Glycerol organosolv pretreatment can unlock lignocellulosic biomass for production of fermentable sugars: Present situation and challenges. Bioresour Technol, 2022, 344: 126264.

[138] Swatloski RP, Spear SK, Holbrey JD, Rogers RD. Dissolution of cellulose with ionic liquids. J Am Chem Soc, 2002, 124: 4974-4975.

[139] Tan X, Zhang Q, Wang W, . Comparison study of organosolv pretreatment on hybrid pennisetum for enzymatic saccharification and lignin isolation. Fuel, 2019, 249: 334-340.

[140] Tang S, Liu R, Sun FF, . Bioprocessing of tea oil fruit hull with acetic acid organosolv pretreatment in combination with alkaline H₂O₂. Biotechnol Biofuels, 2017, 10: 1-12.

[141] Tang S, Dong Q, Fang Z, Miao ZD. Complete recovery of cellulose from rice straw pretreated with ethylene glycol and aluminum chloride for enzymatic hydrolysis. Bioresour Technol, 2019, 284: 98-104.

[142] Tayyab M, Noman A, Islam W, . Bioethanol production from lignocellulosic biomass by environment-friendly pretreatment methods: a review. Appl Ecol Environ Res, 2018, 16: 225-249.

[143] Teng J, Ma H, Wang F, . Catalytic fractionation of raw biomass to biochemicals and organosolv lignin in a methyl isobutyl ketone/H2O biphasic system. ACS Sustain Chem Eng, 2016, 4: 2020-2026.

[144] Teramura H, Sasaki K, Oshima T, . Effective usage of sorghum bagasse: optimization of organosolv pretreatment using 25% 1-butanol and subsequent nanofiltration membrane separation. Bioresour Technol, 2018, 252: 157-164.

[145] Thoresen PP, Matsakas L, Rova U, Christakopoulos P. Recent advances in organosolv fractionation: towards biomass fractionation technology of the future. Bioresour Technol, 2020, 306: 123189.

[146] Trinh LTP, Lee JW, Lee HJ. Acidified glycerol pretreatment for enhanced ethanol production from rice straw. Biomass Bioenerg, 2016, 94: 39-45.

[147] Vaidya AA, Murton KD, Smith DA, Dedual G. A review on organosolv pretreatment of softwood with a focus on enzymatic hydrolysis of cellulose. Biomass Convers Biorefin, 2022, 12: 5427-5442.

[148] Vieira F, Santana HEP, Silva DP, Ruzene DS. A bibliometric description of organosolv pretreatment for coconut waste valorization. Bioenergy Res, 2023

[149] Viola E, Zimbardi F, Morgana M, . Optimized organosolv pretreatment of biomass residues using 2-methyltetrahydrofuran and n-butanol. Processes, 2021, 9: 2051.

[150] Wang Z, Lan T, Zhu J. Lignosulfonate and elevated pH can enhance enzymatic saccharification of lignocelluloses. Biotechnol Biofuels, 2013, 6: 1-10.

[151] Wang Z, He X, Yan L, . Enhancing enzymatic hydrolysis of corn stover by twin-screw extrusion pretreatment. Ind Crops Prod, 2020, 143: 111960.

[152] Wang K, Yang C, Xu X, . 2-Naphthol modification alleviated the inhibition of ethanol organosolv lignin on enzymatic hydrolysis. SSRN Electron J, 2022, 200: 767-776.

[153] Wei W, Wang B, Wang X, . Comparison of acid and alkali catalyzed ethylene glycol organosolv pretreatment for sugar production from bagasse. Bioresour Technol, 2021, 320: 124293.

[154] Wells JM, Drielak E, Surendra KC, Kumar Khanal S. Hot water pretreatment of lignocellulosic biomass: modeling the effects of temperature, enzyme and biomass loadings on sugar yield. Bioresour Technol, 2020, 300: 122593.

[155] Wu Y, Li X, Li F, . Promising seawater hydrothermal combining electro-assisted pretreatment for corn stover valorization within a biorefinery concept. Bioresour Technol, 2022, 351: 127066.

[156] Wyman CE. Aqueous pretreatment of plant biomass for biological and chemical conversion to fuels and chemicals, 2013 John Wiley & Sons

[157] Xu Z, Huang F. Pretreatment methods for bioethanol production. Appl Biochem Biotechnol, 2014, 174: 43-62.

[158] Xu J, Chen H, Kádár Z, . Optimization of microwave pretreatment on wheat straw for ethanol production. Biomass Bioenerg, 2011, 35: 3859-3864.

[159] Xu N, Zhang W, Ren S, . Hemicelluloses negatively affect lignocellulose crystallinity for high biomass digestibility under NaOH and H₂SO₄ pretreatments in Miscanthus. Biotechnol Biofuels, 2012, 5: 1-12.

[160] Yang B, Dai Z, Ding SY, Wyman CE. Enzymatic hydrolysis of cellulosic biomass. Biofuels, 2011, 2: 421-449.

[161] Yang X, Cui C, Zheng A, . Ultrasonic and microwave assisted organosolv pretreatment of pine wood for producing pyrolytic sugars and phenols. Ind Crops Prod, 2020, 157: 112921.

[162] Young RA, Davis JL, Wiesmann E-B. Organic acid pulping of wood—part II. Acetic Acid Pulping of Aspen Holzforschung, 1986, 40: 99-108.

[163] Yu H, Zhang F, Li L, . Boosting levoglucosan and furfural production from corn stalks pyrolysis via electro-assisted seawater pretreatment. Bioresour Technol, 2022, 346: 126478.

[164] Yu K, Ding W-L, Lu Y, . Ionic liquids screening for lignin dissolution: COSMO-RS simulations and experimental characterization. J Mol Liq, 2022, 348: 118007.

[165] Yue H, Zhao Y, Ma X, Gong J. Ethylene glycol: properties, synthesis, and applications. Chem Soc Rev, 2012, 41: 4218-4244.

[166] Zakaria MR, Fujimoto S, Hirata S, Hassan MA. Ball milling pretreatment of oil palm biomass for enhancing enzymatic hydrolysis. Appl Biochem Biotechnol, 2014, 173: 1778-1789.

[167] Zhang T, Kumar R, Wyman CE. Sugar yields from dilute oxalic acid pretreatment of maple wood compared to those with other dilute acids and hot water. Carbohydr Polym, 2013, 92: 334-344.

[168] Zhang K, Pei Z, Wang D. Organic solvent pretreatment of lignocellulosic biomass for biofuels and biochemicals: a review. Bioresour Technol, 2016, 199: 21-33.

[169] Zhang Z, Harrison MD, Rackemann DW, . Organosolv pretreatment of plant biomass for enhanced enzymatic saccharification. Green Chem, 2016, 18: 360-381.

[170] Zhang Y, Hou Q, Fu Y, . One-step fractionation of the main components of bamboo by formic acid-based organosolv process under pressure. J Wood Chem Technol, 2018, 38: 170-182.

[171] Zhao X, Cheng K, Liu D. Organosolv pretreatment of lignocellulosic biomass for enzymatic hydrolysis. Appl Microbiol Biotechnol, 2009, 82: 815-827.

[172] Zhao Y, Liu X, Wang J, Zhang S. Insight into the cosolvent effect of cellulose dissolution in imidazolium-based ionic liquid systems. J Phys Chem B, 2013, 117: 9042-9049.

[173] Zhao X, Li S, Wu R, Liu D. Organosolv fractionating pre-treatment of lignocellulosic biomass for efficient enzymatic saccharification: chemistry, kinetics, and substrate structures. Biofuels Bioprod Biorefin, 2017, 11: 567-590.

[174] Zheng A, Zhao K, Jiang L, . Bridging the gap between pyrolysis and fermentation: improving anhydrosugar production from fast pyrolysis of agriculture and forest residues by microwave-assisted organosolv pretreatment. ACS Sustain Chem Eng, 2016, 4: 5033-5040.

[175] Zhong L, Zhang X, Tang C, . Hydrazine hydrate and organosolv synergetic pretreatment of corn stover to enhance enzymatic saccharification and co-production of high-quality antioxidant lignin. Bioresour Technol, 2018, 268: 677-683.

[176] Zhou Z, Lei F, Li P, Jiang J. Lignocellulosic biomass to biofuels and biochemicals, a comprehensive review with a focus on ethanol organosolv pretreatment technology. Biotechnol Bioeng, 2018, 115: 2683-2702.

[177] Zhou Z, Liu D, Zhao X. Liu Z-H, Ragauskas A. Deconstruction of lignocellulose recalcitrance by organosolv fractionating pretreatment for enzymatic hydrolysis. Emerging technologies for biorefineries, biofuels, and value-added commodities, 2021, Cham: Springer, 23-56.

[178] Zoghlami A, Paës G. Lignocellulosic Biomass: understanding recalcitrance and predicting hydrolysis. Front Chem, 2019, 7: 1-11.