Ternary deep eutectic solvents for effective biomass deconstruction at high solids and low enzyme loadings

Abstract

Ternary deep eutectic solvents (DESs) were developed to enable rapid and high-solid biomass pretreatment as well as concentrated sugar hydrolysate production. Six ternary DESs constituted choline chloride (ChCl) or guanidine hydrochloride (GH) as a hydrogen bond acceptor (HBA), ethylene glycol (EG) or propylene glycol (PG) or glycerin (GLY) as a polyol-based hydrogen bond donor (HBD), and p-toluenesulfonic acid (PTSA) as an acidic HBD. GH-EG-PTSA was the most effective, evidenced by 79% xylan and 82% lignin removal in only 6 min at 120 °C and 10 wt% solid loading. Even at 35 wt% solid loading, both GH-EG-PTSA and ChCl-EG-PTSA still removed more than 60% xylan and lignin in 30 min. Using a 20% solid loading and a low enzyme loading of 5 mg protein/g solid, 128 g/L glucose and 20 g/L xylose was obtained, with a glucose yield of 78.4%. Overall, this study demonstrated novel and high-performance ternary DESs for effective lignocellulose deconstruction.