Preparation of bagasse cellulose and lignin of different qualities using ternary deep eutectic solvents

Deep eutectic solvents (DESs) have gained increasing attention owing to their effectiveness in extracting lignin from biomass. This study aims to investigate the mechanism of selective extraction of lignin from bagasse by adjusting the ratio of oxalic acid (OA) to lactic acid (LA) within a choline chloride (ChCl)-based ternary DES. The objective is to obtain bagasse cellulose and lignin of different qualities. The experimental results indicated that incorporating OA into the ChCl/LA DES system successfully reduced the lignin content in bagasse cellulose from 16.51 wt% to 8.75 wt% and generated bagasse with a more uniform morphology. This study also examined how ratio variations in the ternary DES influenced the molecular weight, degree of polymerization (DP), and elemental/structural compositions of both lignin and bagasse cellulose, thereby providing insights into the underlying mechanisms. The excessive amounts of OA tended to break the β-O-4 bond within lignin and disrupt fiber uniformity. Overall, this study investigated the roles of different components in the ternary DES in producing wood fiber materials of various qualities, providing a theoretical basis for the comprehensive utilization of cellulose materials.