A Review on Chemical Pretreatment of Lignocellulosic Biomass for the Production of Bioproducts: Mechanisms, Challenges and Applications

Main Article Content

Sukunya Areeya
Elizabeth Jayex Panakkal
Malinee Sriariyanun
Tawiwan Kangsadan
Atthasit Tawai
Suksun Amornraksa
Unalome Wetwattana Hartley
Patchanee Yasurin


Excessive dependence on fossil resources to supply the increased energy demands has led to unsustainable growth. Hence, there is a necessity to shift our reliance from non-renewable to renewable resources. In this scenario, lignocellulosic biorefinery gains its importance because lignocellulosic biomass can be converted into various value-added products. However, biomass pretreatment is necessary due to the recalcitrant nature of the biomass. Various pretreatment techniques are employed to convert biomass into a more amenable structure to be utilized in the further steps of biorefinery. Hence, this review concentrates on different chemical pretreatment techniques used currently on biomass along with their modes of action on the biomass. This review will provide a detailed concept of various chemical pretreatments and the recent developments in pretreatment techniques. Despite this, the limitations of the current pretreatment strategies and the difficulties in their industrial applications are also discussed, which could provide innovative ideas to overcome these issues.

Article Details

How to Cite
Areeya, S., Panakkal, E. J., Sriariyanun, M., Kangsadan, T., Tawai, A., Amornraksa, S., Hartley, U. W., & Yasurin, P. (2023). A Review on Chemical Pretreatment of Lignocellulosic Biomass for the Production of Bioproducts: Mechanisms, Challenges and Applications. Applied Science and Engineering Progress, 16(3), 6767. https://doi.org/10.14416/j.asep.2023.02.008
Review Articles


S. Alayont, D. B. Kayan, H. Durak, E. K. Alayont, and S. Genel, “The role of acidic, alkaline and hydrothermal pretreatment on pyrolysis of wild mustard (Sinapis arvensis) on the properties of bio-oil and bio-char,” Bioresource Technology Reports, vol. 17, Feb. 2022, Art. no. 100980.

M. Gunduppalli, Y. S. Cheng, S. Chuetor, D. Bhattacharyya, and M. Sriariyanun, “Effect of dewaxing on saccharification and ethanol production from different lignocellulose biomass,” Bioresource Technology, vol. 339, Nov. 2021, Art. no. 125596.

E. Panakkal and M. Sriariyanun, “Valorization of lignocellulosic biomass to value added products,” The Journal of KMUTNB, vol. 33, no. 1, pp. 1–3, Jan. 2023, doi: 10.14416/j.kmutnb.2022.12.001.

M. P. Gundupalli and M. Sriariyanun, “Recent trends and updates for chemical pretreatment of lignocellulosic biomass,” Applied Science and Engineering Progress, vol. 16, no. 1, 2023, Art. no. 5842, doi: 10.14416/j.asep.2022.03.002.

S. Pant, Ritika, and A. Kuila, “Pretreatment of lignocellulosic biomass for bioethanol production,” Advanced Biofuel Technologies, pp. 177–194, 2022, doi: 10.1016/B978-0-323- 88427-3.00008-8.

T. Ruensodsai and M. Sriariyanun, “Sustainable development and progress of lignocellulose conversion to platform chemicals,” The Journal of KMUTNB, vol. 32, no. 4, 2022, doi: 10.14416/j.kmutnb.2022.03.001.

V. Oriez, J. Peydecastaing, and P. Pontalier, “Lignocellulosic biomass mild alkaline fractionation and resulting extract purification processes: Conditions, yields, and purities,” Clean Technologies, vol. 2, no. 1, pp. 91–115, Feb. 2020.

T. Phusantisampan and N. Kitiborwornkul, “Progress in chemical pretreatment of lignocellulose biomass for applications in biorefinery,” The Journal of KMUTNB, vol. 32, no. 4, 2022, doi: 10.14416/j.kmutnb.2022.09.018.

A. L. Woiciechowski, C. J. D. Neto, L. P. S. Vandenbergh, D. P. C. Neto, A. C. N. Sydney, L. A. J. Letti, S. G. Karp, L. A. Z. Torres, and C. R. Soccol, “Lignocellulosic biomass: Acid and alkaline pretreatments and their effects on biomass recalcitrance – Conventional processing and recent advances,” Bioresource Technology, vol. 304, May 2020, Art. no. 122848.

Y. Su, L. Fang, P. Wang, C. Lai, C. Huang, Z. Ling, and Q. Yong, “Coproduction of xylooligosaccharides and monosaccharides from hardwood by a combination of acetic acid pretreatment, mechanical refining and enzymatic hydrolysis,” Bioresource Technology, vol. 358, May 2020, Art. no. 127365.

M. N. F. Norrrahim, R. A. Ilyas, N. M. Nurazzi, M. S. A. Rani, M. S. N. Atikah, and S. S. Shazleen, “Chemical pretreatment of lignocellulosic biomass for the production of bioproducts: An overview,” Applied Science and Engineering Progress, vol. 14, no. 4, pp. 588–560, Jul. 2021, doi: 10.14416/j.asep.2021.07.004.

J. U. Hernández-Beltrán, I. O. H. Lira, M. M. Cruz-Santos, A. Saucedo-Luevanos, F. Hernández-Terán, and N. Balagurusamy, “Insight into pretreatment methods of lignocellulosic biomass to increase biogas yield: current state, challenges, and opportunities,” Applied Science, vol. 9, no. 18, Jul. 2019, Art. no. 3721.

M. Galbe and O. Wallberg, “Pretreatment for biorefneries: A review of common methods for efcient utilisation of lignocellulosic materials,” Biotechnology for Biofuels, vol. 12, Dec. 2019, Art. no. 294.

E. Sjostrom, Wood Chemistry, 2nd ed. San Diego: Academic Press, 1993.

D. N. S. Hon and N. Shiraishi, Wood and Cellulosic Chemistry, Revised, and Expanded, 2nd ed. Florida: CRC Press, 2001.

S. B. Jamaldheen, M. B. Kurade, B. Basak, C. G. Yoo, K. K. Oh, B. H. Jeon, and T. H. Kim, “A review on physico-chemical delignification as a pretreatment of lignocellulosic biomass for enhanced bioconversion,” Bioresource Technology, vol. 346, Feb. 2022, Art. no. 126591.

M. N. F. Norrrahim, R. A. Ilyas, N. M. Nurazzi, M. S. A. Rani, M. S. N. Atikah, and S. S. Shazleen, “Chemical pretreatment of lignocellulosic biomass for the production of bioproducts: An overview,” Applied Science and Engineering Progress, vol. 14, no. 4, 2021, doi: 10.14416/j. asep.2021.07.004.

W. Zhong, Z. Zhang, W. Qiao, P. Fu, and M. Liu, “Comparison of chemical and biological pretreatment of corn straw for biogas production by anaerobic digestion,” Renewable Energy, vol. 36, no. 6, pp. 1875–1879, Jun. 2011.

P. Bajpai, “Pretreatment of lignocellulosic biomass,” in Pretreatment of Lignocellulosic Biomass for Biofuel Production. Berlin, Germany: Springer, Mar. 2016, pp. 17–70.

H. Chen, J. Liu, X. Chang, D. Chen, Y. Xue, P. Liu, H. Lin, and S. Han, “A review on the pretreatment of lignocellulose for high-value chemicals,” Fuel Processing Technology, vol. 160, pp. 196–206, Jun. 2017.

G. Brodeur, E. Yau, K. Badal, J. Collier, K. B. Ramachandran and S. Ramakrishnan, “Chemical and physicochemical pretreatment of lignocellulosic biomass: A review,” Enzyme Research, vol. 2011, May 2011, doi: 10.4061/ 2011/787532.

P. Wen, Z. Lin, Q. Yang, X. Li, Z. Lian, Y. Xu and J. Zhang, “Two-step hydrogen peroxide-acetic acid and sodium hydroxide-urea pretreatment for saccharification of lignin-rich poplar,” Industrial Crops and Products, vol. 187, Part B, Nov. 2022, Art. no. 115454.

M. Jedrzejczyk, E. Soszka, M. Czapnik, A. M. Ruppert, and J. Grams, “Physical and chemical pretreatment of lignocellulosic biomass,” in Second and Third Generation of Feedstocks. Amsterdam, Netherlands: Elsevier, 2019, pp. 143–196.

M. V. Sivers and G. Zacchi, “A techno-economical comparison of three processes for the production of ethanol from pine,” Bioresource Technology, vol. 51, no. 1, pp. 43–52, 1995.

A. R. Mankar, A. Pandey, A. Modak, and K. K. Pant, “Pretreatment of lignocellulosic biomass: A review on recent advances,” Bioresource Technology, vol. 334, Aug. 2021, Art. no. 25235.

E. J. Panakkal, K. Cheenkachorn, M. P. Gundupalli, N. Kitiborwornkul, and M. Sriariyanun, “Impact of sulfuric acid pretreatment of durian peel on the production of fermentable sugar and ethanol,” Journal of the Indian Chemical Society, vol. 98, no. 12, Dec. 2021, Art. no. 100264.

A. Boontum, J. Phetsom, W. Rodiahwati, K. Kitsubthawee, and T. Kuntothom, “Characterization of diluted-acid pretreatment of water hyacinth,” Applied Science and Engineering Progress, vol. 12, no. 4, 2019, pp. 253–263, doi: 10.14416/j.asep.2019.09.003.

Y. S. Cheng, Z. Y. Wua, and M. Sriariyanun, “Evaluation of Macaranga tanarius as a biomass feedstock for fermentable sugars production,” Bioresource Technology, vol. 294, Dec. 2019, Art. no. 122195.

A. T. W. M. Hendriks and G. Zeeman, “Pretreatments to enhance the digestibility of lignocellulosic biomass,” Bioresource Technology, vol. 100, no. 1, pp. 10–18, Jan. 2009.

W. Den, V. K. Sharma, M. Lee, G. Nadadur, and R. S. Varma, “Lignocellulosic biomass transformations via greener oxidative pretreatment processes: Access to energy and value-added chemicals,” Frontiers in Chemistry, vol. 6, no. 1, pp. 1–23, Apr. 2018.

E. C. Bensah and M. Mensah, “Chemical pretreatment methods for the production of cellulosic ethanol: Technologies and innovations,” International Journal of Chemical Engineering, vol. 2013, 2013, Art. no. 719607.

P. Lenihan, A. Orozco E. O’Neill, M. N. M. Ahmad, D. W. Rooney, and G. M. Walker, “Dilute acid hydrolysis of lignocellulosic biomass,” Chemical Engineering Journal, vol. 156, no. 2, pp. 395–403, Jan. 2010.

A. L. Woiciechowski, C. J. D. Neto, L. P. de S. Vandenberghe, D. P. de C. Neto, A. C. N. Sydney, L. A. J. Letti, S. G. Karpa, L. A. Z. Torres, and C. R. Soccol, “Lignocellulosic biomass: acid and alkaline pretreatments and their effects on biomass recalcitrance – Conventional processing and recent advances,” Bioresource Technology, vol. 304, May 2020, Art. no. 122848.

Y. Luo, Y. Li, L. Cao, J. Zhu, B. Deng, Y. Hou, C. Liang, C. Huang, C. Qin, and S. Yao, “High efficiency and clean separation of eucalyptus components by glycolic acid pretreatment,” Bioresource Technology, vol. 341, Dec. 2021, Art. no. 125757.

E. J. Panakkal, M. Sriariyanun, J. Ratanapoompinyo, P. Yasurin, K. Cheenkachorn, W. Rodiahwati, and P. Tantayotai, “Influence of sulfuric acid pretreatment and inhibitor of sugarcane bagasse on the production of fermentable sugar and ethanol,” Applied Science and Engineering Progress, vol. 15, no. 1, pp. 253–263, 2022, doi: 10.14416/j.asep.2021.07.006.

Y. Zheng, Z. Pan, and R. Zhang, “Overview of biomass pretreatment for cellulosic ethanol production,” International Journal of Agricultural and Biological Engineering, vol. 2, no. 3, 2009, doi: 10.3965/j.issn.1934-6344.2009.03.051-068.

K. Nakason, P. Khemthong, W. Kraithong, S. Mahasandana, and B. Panyapinyopol, “Effect of alkaline pretreatment on the properties of cassava rhizome,” Chemical Engineering Journal, vol. 48, no. 6, pp. 1511–1523, Jun. 2021.

N. A. S. Din, S. J. Lim, M. Y. Maskat, and N. A. M. Zaini, “Bioconversion of coconut husk fibre through biorefinery process of alkaline pretreatment and enzymatic hydrolysis,” Biomass Conversion and Biorefinery, vol. 11, no. 3, pp. 815–826, 2021.

S. Kondaveeti, A. Bisht, R. Pagolu, C. Lai, R. Lestari, A. Kumar, D. Das, V. C. Kalia, and J. Lee,” Mild alkaline pretreatment of rice straw as a feedstock in microbial fuel cells for generation of bioelectricity,” Indian Journal of Microbiology, vol. 62, no. 3, pp. 447–455, Apr. 2022, doi: 10.1007/s12088-022-01022-z.

F. P. Bouxin, S. D. Jackson, and M. C. Jarvis “Organosolv pretreatment of Sitka spruce wood: Conversion of hemicelluloses to ethyl glycosides,” Bioresource Technology, vol. 151, pp. 441–444, Jan. 2014.

X. Zhao, K. Cheng, and D. Liu, “Organosolv pretreatment of lignocellulosic biomass for enzymatic hydrolysis,” Applied Microbiology and Biotechnology, vol. 82, pp. 815–827, Apr. 2009.

P. Kumar, D. M. Barrett, M. J. Delwiche, and P. Stroeve, “Methods for pretreatment of lignocellulosic biomass for eficient hydrolysis and biofuel production,” Industrial and Engineering Chemistry Research, vol. 48, no. 8, pp. 3713– 3729, Mar. 2009, doi: 10.1021/ie801542g.

L. Yao, G. C. Yoo, Y. Pu, X. Meng, W. Muchero, A. G. Tuskan, T. J. Tschaplinski, A. J. Ragauskas, and H. Yang, “Physicochemical changes of cellulose and their infuences on Populus trichocarpa digestibility after diferent pretreatments,” Industrial and Engineering BioResources, vol. 14, no. 4, pp. 9658–9676, Oct. 2019, doi: 10.15376/biores.14.4.9658-9676.

M. G. Papatheofanous, E. Billa, D. P. Koullas, B. Monties, and E. G. Koukios, “Two-stage acid-catalyzed fractionation of lignocellulosic biomass in aqueous ethanol systems at low temperatures,” Bioresource Technology, vol. 54, no. 3, pp. 305–310, 1995.

V. B. Agbor, N. Cicek, R. Sparling, A. Berlin, and D. B. Levin, “Biomass pretreatment: Fundamentals toward application,” Biotechnology Advances, vol. 29, no. 6, pp. 675–685, Nov.–Dec. 2011.

B. Tsegaye, P. Gupta, C. Balomajumder, and P. Roy, “Optimization of Organosolv pretreatment conditions and hydrolysis by Bacillus sp. BMP01 for effective depolymerization of wheat straw biomass,” Biomass Conversion and Biorefinery, vol. 11, pp. 2747–2761, 2021, doi: 10.1007/ s13399-020-00691-4.

A. Soltaninejad, M. Jazini, and K. Karimi, “Biorefinery for efficient xanthan gum, ethanol, and biogas production from potato crop residues,” Biomass and Bioenergy, vol. 158, Mar. 2022, Art. no. 106354.

L. J. Jönsson and C. Martín, “Pretreatment of lignocellulose: formation of inhibitory byproducts and strategies for minimizing their effects,” Bioresource Technology, vol. 19, pp. 103–112, Jan. 2016.

A. W. Bhutto, K. Qureshi, K. Harijan, R. Abro, T. Abbas, A. A. Bazmi, S. Karim, and G. Yu, “Insight into progress in pre-treatment of lignocellulosic biomass,” Energy, vol. 122, pp. 724–745, Mar. 2017.

S. Aziz and K. Sarkanen, “Organosolv pulping: A review,” Tappi Journal, vol. 72, no. 3, pp. 169–175, 1989.

R. Kumar and C. E. Wyman, “Effects of cellulase and xylanase enzymes on the deconstruction of solids from pretreatment of poplar by leading technologies,” Biotechnology Progress, vol. 25, no. 2, pp. 302–314, 2009, doi: 10.1002/btpr.102.

J. M. Gomes, S. S. Silva, and R. L. Reis, “Biocompatible ionic liquids: Fundamental behaviours and applications,” Chemical Society Reviews, vol. 48, no. 15, 2019, doi: 10.1039/ C9CS00016J.

M. Amde, J. Liu, and L. Pang, “Environmental application, fate, efects, and concerns of ionic liquids: A review,” Environmental Science and Technology, vol. 49, no. 21, pp. 12611–12627, Oct. 2015, doi: 10.1021/acs.est.5b03123.

J. T. Gorke, F. Srienc, and R. J. Kazlauskas, “Hydrolase-catalyzed biotransformations in deep eutectic solvents,” Chemical Communications, vol. 10, no. 10, Jan. 2015, doi: 10.1039/ b716317g.

H. Palonen, A. B. Thomsen, M. Tenkanen, A. S. Schmidt, and L. Viikari, “Evaluation of wet oxidation pretreatment for enzymatic hydrolysis of softwood,” Applied Biochemistry and Biotechnology, vol. 117, no. 1, pp. 1–17, Apr. 2004, doi: 10.1385/abab:117:1:01.

C. M. Medina, M. Marcet, and A. B. Bjerre, “Comparison between wet oxidation and steam explosion as pretreatment methods for enzymatic hydrolysis of sugarcane bagasse,” Bioresources, vol. 3, no. 3, pp. 670–683, 2008.

M. Pedersen and A. S. Meyer, “Influence of substrate particle size and wet oxidation on physical surface structures and enzymatic hydrolysis of wheat straw,” Biotechnology Progress, vol. 25, no. 2, pp. 399–408, 2009, doi: 10.1002/btpr.141.

F. Huang, M. P. Singh, and J. A. Ragauskas, “Characterization of milled wood lignin (MWL) in Loblolly pine stem wood, residue, and bark,” Journal of Agricultural and Food Chemistry, vol. 59, no. 24, pp. 12910–12916, Dec. 2011, doi: 10.1021/jf202701b.

M. P. Pandey and C. S. Kim, “Lignin depolymerization and conversion: A review of thermos-chemical methods,” Chemical Engineering and Technology, vol. 34, pp. 29–41, Nov. 2010, doi: 10.1002/CEAT.201000270.

S. K. Uppal, R. Kaur, and P. Sharma, “Optimization of chemical pretreatment and acid saccharification for conversion of sugarcane bagasse to ethanol Sugar,” Sugar Tech, vol. 13, no. 3, pp. 214–219, Aug. 2011, doi: 10.1007/s12355-011-0091-3.

J. D. DeMartini, S. Pattathil, U. Avci, K. Szekalski, K. Mazumder, M. G. Hahn, and C. E. Wyman, “Application of monoclonal antibodies to investigate plant cell wall deconstruction for biofuels production,” Energy & Environmental Science, vol. 4, no. 10, pp. 4332–4339, 2011, doi: 10.1039/ C1EE02112E.

P. Alvira, E. Tomas-Pejo, M. Ballesteros, and J. M. Negro, “Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: A review,” Bioresource Technology, vol. 101, no. 13, pp. 4851–4861, Jul. 2010.

J. W. Lee and T. W. Jeffries, “Efficiencies of acid catalysts in the hydrolysis of lignocellulosic biomass over a range of combined severity factors,” Bioresource Technology, vol. 102, no. 10, pp. 5884–5890, May 2011.

A. Xingye, R. Zhang, L. Liu, J. Yang, Z. Tian, G. Yang, H. Cao, Z. Cheng, Y Ni, and H. Liu, “Ozone pretreatment facilitating cellulase hydrolysis of unbleached bamboo pulp for improved fiber flexibility,” Industrial Crops and Products, vol. 178, Apr. 2022, Art. no. 114577.

N. Novia, H. Hasanudin, H. Hermansyah, and A. Fudholi, “Kinetics of lignin removal from rice husk using hydrogen peroxide and combined hydrogen peroxide–aqueous ammonia pretreatments,” Fermentation, vol. 8, no. 4, Apr. 2022, doi: 10.3390/fermentation8040157.

Y. Han, Y. Bai, J. Zhang, D. Liu, and X. Zhao, “A comparison of diferent oxidative pretreatments on polysaccharide hydrolyzability and cell wall structure for interpreting the greatly improved enzymatic digestibility of sugarcane bagasse by delignifcation,” Bioresources and Bioprocessing, vol. 7, May 2020, Art. no. 24.

M. Sriariyanun, J. H. Heitz, P. Yasurin, S. Asavasanti, and P. Tantayotai, “Itaconic acid: A promising and sustainable platform chemical?,” Applied Science and Engineering Progress, vol. 12, no. 2, pp. 75–82, 2019, doi: 10.14416/ j.asep.2019.05.002.

S. Chuetor, E. J. Panakkal, T. Ruensodsai, K. Cheenkachorn, S. Kirdponpattara, Y. S. Cheng, and M. Sriariyanun, “Improvement of enzymatic saccharification and ethanol production from rice straw by recycled ionic liquid: Effect of antisolvent mixture,” Bioengineering, vol. 9, no. 3, Mar. 2022, doi: 10.3390/bioengineering9030115.

R. Alayoubi, N. Mehmood, E. Husson, A. Kouzayha, M. Tabcheh., L. Chaveriat, C. Sarazin, and I. Gosselin, “Low temperature ionic liquid pretreatment of lignocellulosic biomass to enhance bioethanol yield,” Renewable Energy, vol. 145, pp. 1808–1816, Jan. 2020.

S. P. F. Costa, A. M. O. Azevedo, P. C. A. G. Pinto, and M. L. M. F. S. Saraiva, “Environmental impact of ionic liquids: Recent advances in (Eco) toxicology and (Bio) degradability,” ChemSusChem, vol. 10, no. 11, pp. 2321–2347, Jun. 2017, doi: 10.1002/cssc.201700261.

S. Morales-delaRosa, J. M. Campos-Martin, and J. L. G. Fierro, “High glucose yields from the hydrolysis of cellulose dissolved in ionic liquids,” Chemical Engineering Journal, vol. 181–182, pp. 538–541, Feb. 2012.

M. P. Gundupalli, K. Bano, T. K. Panda, M. Sriariyanun, and D. Bhattacharyya, “Understanding the effect of low concentrated protic ionic liquids (PILs) on coconut (Cocos nucifera) residues,” Biomass Conversion and Biorefinery, Mar. 2022, doi: 10.1007/s13399-022-02572-4.

S. P. M. Ventura, L. D. F. Santos, J. A. Saraiva, and J. A. P. Coutinho, “Concentration effect of hydrophilic ionic liquids on the enzymatic activity of Candida antarctica lipase B,” World Journal of Microbiology and Biotechnology, vol. 28, no. 6, pp. 2303–2310, Jun. 2012, doi: 10.1007/s11274-012-1037-y.

A. S. Amarasekara and B. Wiredu, “Bronsted acidic ionic liquid 1-(1-propylsulfonic)-3- methylimidazolium-chloride catalyzed hydrolysis of D -cellobiose in aqueous medium,” International Journal of Carbohydrate Chemistry, 2012, doi: 10.1155/2012/948652.

M. Sriariyanun and K. Kitsubthawee, “Trends in lignocellulosic biorefinery for production of value-added biochemicals,” Applied Science and Engineering Progress, vol. 13, no. 4, pp. 283– 284, 2020, doi: 10.14416/j.asep.2020.02.005.

C. G. Yoo, Y. Pu, and A. J. Ragauskas, “Ionic liquids: Promising green solvents for lignocellulosic biomass utilization,” Current Opinion in Green and Sustainable Chemistry, vol. 5, no. 9, pp. 5–11, Jun. 2017.

S. Singh, B. A. Simmons, and K. P. Vogel, “Visualization of biomass solubilization and cellulose regeneration during ionic liquid pretreatment of switchgrass,” Biotechnology and Bioengineering, vol. 104, no. 1, pp. 68–75, Sep. 2009, doi: 10.1002/bit.22386.

B. Li, J. Asikkala, I. Filpponen, and D. S. Argyropoulos, “Factors affecting wood dissolution and regeneration of ionic liquids,” Industrial & Engineering Chemistry Research, vol. 49, no. 5, pp. 2477–2484, Jan. 2010, doi: 10.1021/ie 901560p.

S. Zhu, “Use of ionic liquids for the efficient utilization of lignocellulosic materials,” Journal of Chemical Technology and Biotechnology, vol. 83, pp. 777–779, Feb. 2008.

P. Tantayotai, M. P. Gundupalli, E. J. Panakkal, M. Sriariyanun, K. Rattanaporn, and D. Bhattacharyya, “Differential influence of imidazolium ionic liquid on cellulase kinetics in saccharification of cellulose and lignocellulosic biomass substrate,” Applied Science and Engineering Progress, vol. 15, no. 3, 2022, doi: 10.14416/j.asep.2021.11.003.

P. Tantayotai, K. Rattanaporn, S. Tepaamorndech, K. Cheenkachorn, and Malinee Sriariyanun, “Analysis of an ionic liquid and salt tolerant microbial consortium which is useful for enhancement of enzymatic hydrolysis and biogas production,” Waste and Biomass Valorization, vol. 10, pp. 1481–1491, 2019.

P. Tantayotai, P. Rachmontree, W. Rodiahwati, K. Rattanaporn, M. Sriariyanun, “Production of ionic liquid-tolerant cellulase produced by microbial consortium and its application in biofuel production,” Energy Procedia, vol. 100, pp. 155–159, Nov. 2016.

Z. Liu, L. Li, C. Liu, and A. Xu, “Saccharifcation of cellulose in the ionic liquids and glucose recovery,” Renewable Energy, vol. 106, pp. 99– 102, Jun. 2017.

Z. Yuan, G. E. Klinger, S. Nikafshar, Y. Cui, Z. Fang, M. Alherech, S. Goes, C. Anson, S. K. Singh, B. Bals, D. B. Hodge, M. Nejad, S. S. Stahl, and E. L. Hegg, “Effective biomass fractionation through oxygen - Enhanced alkaline - Oxidative pretreatment,” ACS Sustainable Chemistry and Engineering, vol. 9, no. 3, pp. 1118– 1127, Jan. 2021, doi: 10.1021/acssuschemeng. 0c06170.

I. Mehrez, K. Chandrasekhar, W. Kim, S. H. Kim, and G. Kumar, “Comparison of alkali and ionic liquid pretreatment methods on the biochemical methane potential of date palm waste biomass,” Bioresource Technology, vol. 360, Sep. 2022, Art. no. 127505.

J. Sun, R. Ding, and J. Yin, “Pretreatment of corn cobs and corn stalks with tetrabutyl phosphate hydroxide ionic liquid to enhance enzymatic hydrolysis process,” Biochemical Engineering Journal, vol. 177, Jan. 2022, Art. no. 108270.

P. Suwannabun, K. Cheenkachorn, M. Prongjit, A. Tawai, and M Sriariyanun, “Pretreatment of Rice Straw by Inorganic Salts and 1-Ethyl- 3-methylimdazolium Acetate for Biofuel Production,” in 2nd Asia Conference on Energy and Environment Engineering (ACEEE), 2019, pp. 12–15.

D. Jose, N. Raina, R. Deepakkumar, E. J. Panakkal, M. Sriariyanun, and T. Kangsadan, “The combined effect of inorganic salt and ionic liquid in pretreatment on enzymatic saccharification of rice straw,” E3S Web Conferences, vol. 355, no. 4, pp. 1–5, Aug. 2022, doi: 10.1051/e3sconf/ 202235501002.

J. Gao, C. Chen, L. Wang, Y. Lei, H. Ji, and S. Liu, “Utilization of inorganic salts as adjuvants for ionic liquid–water pretreatment of lignocellulosic biomass: enzymatic hydrolysis and ionic liquid recycle,” The Journal of Physical Chemistry B, vol. 121, no. 16, pp. 4202–4212, Apr. 2017.

A. Pandey, Bhawna, D. Dhingra, and S. Pandey, “Hydrogen bond donor/acceptor co-solvent modified choline chloride-based deep eutectic solvents,” 3 Biotech, vol. 9, no. 7, pp. 1–10, Jul. 2019.

E. L. Smith, A. P. Abbott, and K. S. Ryder, “Deep eutectic solvents (DESs) and their applications,” Chemical Reviews, vol. 114, no. 21, pp. 11060– 11082, Oct. 2014, doi: 10.1021/cr300162p.

Y. Yu, D. Wang, L. Chen, H. Qi, A. Liu, M. Deng, X. Wu, and K. Wang, “Recyclable choline chloride-based deep eutectic solvent pretreatment for accelerated enzymatic digestibility of Triarrhena lutarioriparia,” Industrial Crops and Products, vol. 187, Nov. 2022, Art. no. 115542.

L. Yang, T. Zheng, C. Huang, and J. Yao “Using deep eutectic solvent pretreatment for enhanced enzymatic saccharification and lignin utilization of masson pine,” Renewable Energy, vol. 195, pp. 681–687, Aug. 2022.

N. Li, F. Meng, H. Yang, Z. Shi, P. Zhao, and J. Yang “Enhancing enzymatic digestibility of bamboo residues using a three-constituent deep eutectic solvent pretreatment,” Bioresource Technology, vol. 346, Dec. 2021, doi: 10.1016/j. biortech.2021.126639.

E. J. Panakkal, K. Cheenkachorn, M. P. Gundupalli, N. Kitiborwornkul, and M. Sriariyanun, “Impact of sulfuric acid pretreatment of durian peel on the production of fermentable sugar and ethanol,” Journal of the Indian Chemical Society, vol. 98, no. 12, Dec. 2021, Art. no. 100264.

E. J. Panakkal, K. Cheenkachorn, S. Chuetor, P. Tantayotai, N. Raina, Y. S. Cheng, M. Sriariyanun, “Optimization of deep eutectic solvent pretreatment for bioethanol production from Napier grass,” Sustainable Energy Technologies and Assessments, vol. 54, Dec. 2022, Art. no. 102856.

V. T. Ribeiro, A. C. Campolina, W. A. Costa, C. E. A. Padilha, J. D. B. C. Filho, A. L. O. Sá Leitão, J. C. Rocha, and E. S. Santos, “Ethanol production from green coconut fiber using a sequential steam explosion and alkaline pretreatment,” Biomass Conversion and Biorefinery, Jul. 2022, doi: 10.1007/s13399-022-03100-0.

D. Jose, N. Kitiborwornkul, M. Sriariyanun, and K. Keerthi, “A review on chemical pretreatment methods of lignocellulosic biomass: Recent advances and progress,” Applied Science and Engineering Progress, vol. 15, no. 4, 2022, doi: 10.14416/j.asep.2022.08. 001.

A. Nadif, D. Hunkeler, and P. Käuper, “Sulfurfree lignins from alkaline pulping tested in mortar for use as mortar additives,” Bioresource Technology, vol. 84, no. 1, pp. 49–55, Aug. 2002.

S. Kim and M. T. Holtzapple, “Lime pretreatment and enzymatic hydrolysis of corn stover,” Bioresource Technology, vol. 96, no. 18, pp. 1994– 2006, Dec. 2005.

V. S. Chang, W. E. Kaar, B. Burr, and M. T. Holtzapple, “Simultaneous saccharification and fermentation of lime-treated biomass,” Biotechnology Letters, vol. 23, no. 16, pp. 1327– 1333, Aug. 2001, doi: 10.1023/A:10105 94027988.

A. Satlewal, R. Agrawal, S. Bhagia, J. Sangoro, and J. A. Ragauskas, “Natural deep eutectic solvents for lignocellulosic biomass pretreatment: recent developments, challenges and novel opportunities,” Biotechnology Advances, vol. 36, no. 8, pp. 2032–2050, Dec. 2018.