Mild Fractionation of Biomass into Three Binary-Component Fractions

The effective fractionation technology route is a crucial aspect for the full valorization of lignocellulose. The current fractionation technologies primarily focus on single-component fractionation of lignocellulose, with the technical dilemma between each component conversion availability and overall product yields, especially under harsh fractionation conditions. This work proposed the mild fractionation process of a mechanochemistry-assisted choline hydroxide-ethylene glycol alkaline deep eutectic solvent (Ch-Ely DES) to fractionate straw biomass, with the goal of higher-value binary-component fractions pursuing, i.e., holocellulose, lignin-carbohydrate complexes (LCC), and arabinoxylan (AX). Through the synergistic effect of mechanochemical deconstruction and alkaline deep eutectic solvent swelling, 93% holocellulose recovery, corresponding to a 53.2/100 Ar β-O-4 bond content in the LCC fraction, was achieved. The resulting holocellulose hydrolysis values at a 5 wt % solid loading were 96 and 55% for glucose and xylose respectively. The mild fractionation process could yield fractions with well-preserved structures by selective hydrogen bond network interaction and lignin-carbohydrate complex covalent bond preservation. The proposed binary-component fractionation route is promising to diversify current fractionation technologies and product streams.