Lignin-derived deep eutectic solvent for enhanced corn straw pretreatment: Boosting enzymatic hydrolysis and biohydrogen production

This study assessed the effectiveness of an innovative lignin-based deep eutectic solvent (DES) formulated with vanillin (VAN) as the hydrogen bond donor and choline chloride (ChCl) as the hydrogen bond acceptor. The effects of ChCl/VAN DES pretreatment on the chemical composition, enzymatic digestibility, and biohydrogen production of corn straw were systematically investigated. The hydrated DES containing 30 % water exhibited remarkable pretreatment efficiency, achieving 61.4 % delignification, 58.1 % hemicellulose removal, and preserving a high cellulose retention (85.5 %). Compared to the raw straw, the enzymatic hydrolysis efficiency of the DES-pretreated residue showed a substantial increase from 27.6 % to 85.0 %. During sequential dark fermentation, the cumulative hydrogen yield reached 116.9 mL/g total solids (TS), marking a 1.95-fold increase compared to the control group (39.6 mL/g TS). The proposed lignin-derived DES demonstrates promising potential as an efficient solvent for biomass fractionation. • Lignin-derived DES was proposed for the pretreatment of corn straw. • Lignin-derived DES system effectively disrupted the structure of corn straw. • The highest enzymatic hydrolysis efficiency reached 85.0 % at 140 °C for 3 h. • A maximum biohydrogen yield of 116.9 mL/g total solids was achieved.