Hydrothermal pretreatment optimization and deep eutectic solvent pretreatment of lignocellulosic biomass: An integrated approach

Authors: GUNDUPALLI, MARTTIN - King Mongkut'S Institute Of Technology Ladkrabang; TANTAYOTAI, PRAPAKORN - Srinakharinwirot University; PANAKKAL, ELIZABETH - King Mongkut'S Institute Of Technology Ladkrabang; CHUETOR, SANTI - King Mongkut'S Institute Of Technology Ladkrabang; KIRDPONPATTARA, SUCHATA - King Mongkut'S Institute Of Technology Ladkrabang; THOMAS, ANNE - Vellore Institute Of Technology, Vit; Sharma, Brajendra - Bk; SRIARIYANUN, MALINEE - King Mongkut'S Institute Of Technology Ladkrabang

Submitted to: Bioresource Technology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2022
Publication Date: 1/18/2022
Citation: Gundupalli, M.P., Tantayotai, P., Panakkal, E.J., Chuetor, S., Kirdponpattara, S., Thomas, A.S., Sharma, B.K., Sriariyanun, M. 2022. Hydrothermal pretreatment optimization and deep eutectic solvent pretreatment of lignocellulosic biomass: An integrated approach. Bioresource Technology Reports. https://doi.org/10.1016/j.biteb.2022.100957.
DOI: https://doi.org/10.1016/j.biteb.2022.100957

Interpretive Summary: Biomass pretreatment is an essential step in the process of producing ethanol from biomass. There are various pretreatment methods with their own merits and demerits. One of the methods, hydrothermal pretreatment is a chemical-free, cost-effective and eco-friendly process. Although hydrolysis of hemicellulose can be achieved during hydrothermal pretreatment, the yield of glucose monomer is low compared to other pretreatment methods. In this work, we have shown that this problem can be overcome through an integrated approach of combining hydrothermal with a chemical method. The outcome from this work will help improve the economics of lignocellulosic ethanol production and thereby help farmers by increasing the value of waste biomass generated on the farms.

Technical Abstract: The combined effect of hydrothermal (HT) and deep eutectic solvent (DES) pretreatment on hemicellulose and lignin removal was studied to enhance cellulose digestibility during saccharification. The operating conditions (water loading and time) for HT pretreatment of sugarcane bagasse (SB) were optimized using response surface methodology (RSM). The SB optimum conditions were applied to other biomass with similar lignin and hemicellulose composition (rice straw (RS) and napier grass (NG)). The HT solids were further subjected to DES pretreatment using ChCl/LA (1:2). The pretreatment efficiency was compared between untreated, HT, ChCl/LA, and HT-ChCl/LA treated solids based on the glucose yield during saccharification. The hemicellulose recovery and delignification were higher in HT-ChCl/LA solids compared to HT and ChCl/LA pretreated solids. During saccharification (72h) of HT-ChCl/LA solids, the glucose yield increased 3.06, 3.41, and 2.89-fold times for SB, RS, and NG, respectively. Hemicellulose and lignin obtained at different pretreatment stages could benefit the biorefineries.