Efficient Fast Fractionation of Biomass Using a Diol-Based Deep Eutectic Solvent for Facilitating Enzymatic Hydrolysis and Obtaining High-Quality Lignin

Abstract

Current DES pretreatment is often performed under relatively severe conditions with high temperature, long time, and high DES usage. This work studied a short-time diol DES (deep eutectic solvent) pretreatment under mild conditions to fractionate the bamboo, facilitate enzymatic hydrolysis, and obtain high-quality lignin. At an optimized condition of 130 °C for only 10 min, lignin and xylan removal reached 61.34 % and 84.15 %, with residual glucan showing a ~90 % enzymatic hydrolysis yield. Equally important, the dissolved lignin could be readily recovered with 97.51 % yield, exhibiting 96.65 % β-O-4 preservation. The fractionation and lignin protection mechanisms were unveiled by XRD, FTIR, cellulose-DP, 2D HSQC NMR, 31P NMR and GPC analysis. This study highlighted that short-time fractionation of bamboo can be achieved by a diol-based DES which is an ideal strategy to upgrade the lignocellulose biomass for high enzymatic hydrolysis yields and high-quality lignin stream.