Microwave-assisted ternary deep eutectic solvent (DES) for lignin removal from corn straw

To achieve efficient lignin removal while preserving cellulose, ternary deep eutectic solvents (DESs) incorporating Lewis acids were prepared for the microwave-assisted pretreatment of corn stover. The effects of Lewis acid types and pretreatment conditions on delignification were investigated, and the structural characteristics of corn stover samples before and after pretreatment were characterized. The results indicated that the ternary DES composed of choline chloride (ChCl), FeCl 3 , and ethylene glycol (EG), denoted as ChCl-FeCl 3 -EG, exhibited optimal performance. Under the conditions of a pretreatment time of 41 min, a temperature of 134 °C, a liquid-solid ratio of 13.80, and a Lewis acid-to-ChCl molar ratio of 0.086, the removal rates of lignin and hemicellulose reached 92.24% and 87.99%, respectively, while the cellulose retention rate reached 94.03%. Compared with traditional oil bath heating, microwave assistance not only enhanced lignin removal efficiency but also significantly shortened the processing time. Furthermore, the mechanism of the ChCl-FeCl 3 -EG pretreatment process for corn stover was analyzed. The DES system achieved efficient separation of corn stover components through the synergistic effects of “acid catalysis, hydrogen bond disruption, and selective dissolution,” providing a green pretreatment pathway for biorefining.