A novel deep eutectic solvent from lignin-derived acids for improving the enzymatic digestibility of herbal residues from cellulose

A novel lignin-derived deep eutectic solvent (DES) was synthesized from choline chloride (ChCl) and p-coumaric acid (PCA). The results showed that after pretreatment with lignin-derived DES, the dense cellulose-hemicellulose-lignin structure of herb residues of Cortex albiziae (HRCA) was effectively broken down and this facilitated subsequent enzymatic hydrolysis. The optimum pretreatment conditions were ChCl/PCA molar ratio of 1:1, 160 degrees C-5h, and a solid-liquid ratio of 1:10. Compared with untreated HRCA, 72-h enzymatic digestibility increased from 48.08 to 84.62%. When a ChCl-PCA-water pretreatment was used, the 72-h digestibility level of the residue reached 99.36%. Moreover, the recycling and reusability of this novel DES were evaluated. The results showed that synthesis and utilization of green, environment-friendly and recyclable lignin-derived DES can offer a new way of utilizing lignin which has considerable potential in the refining of biomass. [GRAPHICS] .