Investigation of a Na2S-assisted deep eutectic solvent pretreatment for enhanced cellulose/xylan saccharification and high-quality lignin with abundant ether bond

Herein, a novel Na2S-facilitated deep eutectic solvent (DES) pretreatment using choline chloride/ethylene gly-col/sodium sulfide system (ChCl/EG/Na2S) was proposed to fractionate moso bamboo (MB), which could result in as high as 70.93% lignin removal, while glucan and xylan showed high recovery of 93.83% and 55.59%, accompanied by excellent enzymatic digestibility. Remarkably, the recovered lignin possessed a high recovery yield (80.59%), which contained high beta-O-4 bond content of 21.74-40.45/100Ar with very limited condensation structures. The fractionation behavior of the DES was investigated by composition analysis, SEM, FQA, FTIR, GPC, and NMR which revealed its working mechanism. This study highlighted that the Na2S DES could preserve most cellulose and hemicellulose in the solid while removing lignin substantially with intact structure, which contributes to the valorization of both carbohydrates and lignin in the biomass.

Automated summary

A novel Na2S-facilitated DES pretreatment method was proposed to fractionate moso bamboo, which achieved high lignin removal and preserved most cellulose and hemicellulose with excellent enzymatic digestibility.