Boosting Lignin\nDissolution and Biomass Fractionation\nby Innovative Alkaline Deep Eutectic Solvents

Utilization of deep eutectic solvents (DESs) to extract\nlignin\nis a highly attractive strategy for biomass upgrading. Although acidic\nDESs have been extensively investigated, alkaline DESs (ADESs) have\nrarely been applied in lignin extraction. Herein, several promising\nADESs were prepared for lignin dissolution and biomass pretreatment.\nLignin solubility showed a good positive correlation with the Kamlet–Taft\nparameters and the basicities of the prepared ADESs. Notably, the\nhighest solubility of alkali lignin (AL), enzymatically hydrolyzed\nlignin (EHL), kraft lignin (KL), and dealkaline lignin (DAL) could\nreach 49.85, 49.46, 53.14, and 53.17 wt % in ADESs at 60 °C,\nrespectively. Importantly, the prepared ADESs could efficiently remove\nlignin (80.9–97.8%) from corn stover at 120 °C, significantly\nimproving the enzymatic efficiencies of the residues (71.5–85.4%).\nBesides, lignin with relatively intact structures or lignin fragments\nwith low molecular weight and good dispersion could be successfully\ngenerated. These results confirmed the great potential of ADESs for\nbiomass upgrading.