Efficient fractionation of biomass by acid deep eutectic solvent (DES) and rapid preparation of lignin nanoparticles

Efficient fractionation and valorization of biomass major components are important for biomass utilization. Deep eutectic solvent (DES) treatment is a promising method for biomass processing. In this study, a choline chloride oxalic acid dihydrate (ChCl-OA) DES treatment method was developed to efficiently separates biomass components and isolate the lignin from bamboo. Hemicellulose (from 16.2 to 3.2%) and lignin (from 27.4 to 4.9%) components in recovery solid were significantly reduced. Results revealed that the DES-extracted lignin (DESL) had a higher yield (82.1%) and purity (94.9%), but a lower molecular weight (1148 g/mol) compared with the milling wood lignin (MWL) and alkali lignin (AL). Meanwhile, the DESL from the acid DES pretreatment of bamboo biomass was beneficial to the preparation of stable and homogenous lignin nanoparticles (LNPs). This study provides an efficient method to separate the main components of biomass and prepare LNPs. The DES treatment showed great potential for biomass component fractionation and lignin valorization.