Effect of different washing methods on reducing the inhibition of surface lignin in the tetraethylammonium chloride/oxalic acid-based deep eutectic solvent pretreatment

Abstract

During the biomass pretreatment , the formation and repolymerization of lignin droplets on the surface of cell wall has a negative impact on the cellulose accessibility and enzymatic saccharification . When D. sinicus (DS) was treated with tetraethylammonium chloride/Oxalic acid-based deep eutectic solvent (TEAC/OA) at 120 °C and 7 h, the sodium carbonate and sodium hydroxide washing of pretreated residues decreased the surface lignin content by about 27 % as compared to that cleaned with hot water, which can generate more cellulose accessible sites for enzymatic digestibility . Finally, the higher glucose yields of 70.69 % for sodium carbonate washing and 76.25 % for sodium hydroxide washing were achieved. This work provided an insight to overcome the negative effects of surface lignin and open a window for the efficient bamboo biorefinery of DES systems in southwest China. • A DES pretreatment of TEAC/OA was developed for the bamboo residues biorefinery. • Organic solvent washing can reduce the surface lignin content in pretreated bamboo. • Cellulose accessibility of DS-SC and DS-SH improved by about 1.5 times than DS-DW. • Glucose yield of 70.69 % for DS-SC and 76.25 % for DS-SH was achieved.