Investigation of the effects of ternary deep eutectic solvent composition on pretreatment of sorghum stover

Biomass-derived deep eutectic solvents (DESs) have been introduced as promising pretreatment and fractionation solvents because of their mild processing conditions, easy synthesis, and green solvent components from biomass. In recent DES studies, solvent-based third constituents like water, ethanol, and others improve the processibility of typical binary DESs. However, the impacts of these components are not well understood. Here, two solvent-based constituents, including water and ethylene glycol, were applied to 3,4-dihydroxybenzoic acid (DHBA)-based DES system for improving the conversion efficiency of cellulose-rich fraction and the properties of lignin fraction. Chemical composition, enzymatic digestibility, degree of polymerization of cellulose and physicochemical properties of lignin were used to evaluate the impact of each third constituent on biomass processing. Ternary ChCl-DHBA DESs exhibited better performances in delignification, fermentable sugar production, and preservation of beta-O-4 ether linkage in lignin compared with binary ChCl-DHBA DES.

Automated summary

Biomass-derived deep eutectic solvents (DESs) have shown promise as pretreatment and fractionation solvents for biomass due to their mild processing conditions, easy synthesis, and green components. In this study, the effects of water and ethylene glycol as solvent-based third constituents on biomass processing were evaluated using various parameters. The results showed that ternary ChCl-DHBA DESs outperformed binary ChCl-DHBA DES in terms of delignification, fermentable sugar production, and preservation of beta-O-4 ether linkage in lignin.