Development of novel ternary deep eutectic pretreatment solvents from lignin-derived phenol, and its efficiency in delignification and enzymatic hydrolysis of peanut shells

This work evaluated the effectiveness of a novel deep eutectic solvents (DES) prepared from guaiacol (GG), and p-hydroxybenzoic acid (PB) as a double hydrogen bond donor and choline chloride (ChCl) as a hydrogen bond receptor. The effect of ChCl-GG-PB on the structural properties and enzymatic hydrolysis of peanut shell was analyzed. Furthermore, the performance of ChCl-GG-PB as a hydrogen bond donor was compared with two other DES of PB and GG as hydrogen bond donors, and the effects of molar ratio, temperature and time were studied. The results showed that after ChCl-GG-PB pretreatment, hemicellulose and lignin were effectively removed, the removal rate was about 63.36% and 69.54%, respectively, and the enzymatic glycosaccharification efficiency was significantly improved, of which the xylose content was 5.5 times higher than the untreated. In addition, ChCl-GG-PB pretreated showed significant changes in the structure and morphology, with the highest crystallinity and lowest solid recovery. These results affirms that the proposed novel ternary DES is a promising pretreatment solvent that can effectively deconstruct lignocellulose and improve cellulose digestibility, thereby achieving an economically viable biomass conversion method.