Facilitating enzymatic hydrolysis with a novel guaiacol-based deep eutectic solvent pretreatment

Herein, we established a novel deep eutectic solvent (DES) using lignin-derived guaiacol as hydrogen bond donor (HBD). The sole ChCl/guaiacol system was found to be inefficient for the fractionation of wheat straw (WS), while the incorporation of trace AlCl3 significantly facilitated the degradation of hemicellulose and lignin, resulting in a complete enzymatic digestibility of the pretreated WS. Further, this study revealed that the DES-degraded lignin was readily precipitated during the washing process, and thus hindered the enzymatic hydrolysis of poplar and bamboo (with hydrolysis yield of 42.03% and 71.67%, respectively). Alkali washing offers a possible approach to remove the precipitated lignin, after which a near 100% hydrolysis yield was also obtained for poplar and bamboo.

Automated summary

The study shows that the addition of trace AlCl3 during the enzymatic degradation process using DES can significantly enhance the degradation of hemicellulose and lignin, improving the enzymatic digestibility of pretreated plant fibers. Alkali washing is a feasible method to remove the precipitated lignin after degradation, which can significantly increase the enzymatic hydrolysis efficiency of the materials.