Efficient fractionation of kenaf chemical components by using recyclable acidic DES

Phloem biomass has gradually attracted attention for its conversion and utilization due to its fast growth rate and suitability for textile use. Currently, clean methods for separating the chemical components of biomass have attracted attention. In this study, the choline chloride-lactic acid (CLA) and choline chloride-glycolic acid (CGA) pretreatment were developed for kenaf chemical components separation, and the solid residue and regenerated lignin were characterized. The results demonstrated that two acidic deep eutectic solvents (DESs) pretreatment had good removal capacities for lignin and hemicellulose even when the kenaf was not crushed. Under optimal treatment conditions, the retention rates of cellulose were 82.4% and 81.1%, respectively. The cellulose content in the recovery solids residues reached 91.5% and 91.3%, which also resulted in good enzymatic hydrolysis conversion efficiency (85.4% and 84.9%). The regenerated lignin exhibited high purity (91.9% and 90.1%), and low molecular weight (1209 and 1086 g/mol), which was attributed to the amount of ether bonds cleavage in lignin. Meanwhile, the DES exhibited a good ability to recycle and reuse. Overall, acidic DES pretreatment holds promise for efficient fractionation and component utilization of kenaf phloem biomass.