Highly efficient conversion of cellulose and hemicellulose using an innovative ternary deep eutectic solvent: Achieving the green and complete use of lignocellulose

Efficient pretreatment plays a key role in enhancing lignocellulose resources utilization. This study introduces a novel lignocellulose conversion approach using a newly developed ternary deep eutectic solvents (DES) consisting of Choline Chloride, Urea, and Ethylenediamine (ChCl-U-EDA 1:1.4:0.6). The enzymatic efficiencies of cellulase and hemicellulase reached 90.99 % and 76.77 %, respectively. Under the condition of 110 °C, 90 min, and a 1:15 solid to liquid ratio, the enzymatic hydrolysis of DES-pretreated lignocellulose yielded glucose and xylose at 0.52 g/g and 0.21 g/g, respectively. The lignin isolated from ChCl-U-EDA pretreatment displayed a more preserved structure with enhanced retention of β-O-4 bonds. Reduced density gradient analysis and molecular dynamics simulation indicated that the hydrogen bonding between lignin and ChCl-U-EDA facilitates the detachment of lignin from lignocellulose. The extracted lignin was then fabricated into a hydrogel for yeast immobilization, facilitating bioethanol production from glucose and xylose. After ten cycles, the average sugar to ethanol conversion was 0.448 g/g, corresponding to 89.6 % sugar conversion to ethanol. Reuse of ChCl-U-EDA resulted in 62.13 % lignin collection after 5 cycles. This study proposes a novel approach for the comprehensive and sustainable conversion of lignocellulose in an environmentally friendly and efficient manner.