One-Step Acid Bleachable Pretreatment with a Recyclable Acid Hydrotrope and Chlorate for Biomass Valorization

Abstract

Pretreatment is a necessary step to converting lignocellulosic biomass from its native form into a more accessible form for the value-added utilization of its main components. Herein, we developed a one-step acid bleachable pretreatment method using a recyclable acid hydrotrope (p-toluenesulfonic acid, p-TsOH) and chlorate to achieve the fibers bleaching and lignin extraction simultaneously. Under a pretreatment condition of a p-TsOH concentration of 80 wt.%, a pretreatment temperature of 80 °C, and a pretreatment time of 45 min, 84.33% of hemicelluloses and 76.79% of lignin were dissolved out from poplar wood. The obtained dispersed solids with a whiteness of 60.13% can be used for papermaking or ethanol production. The results from quasi-simultaneous enzymatic saccharification and combined fermentation (Q-SSF) of the pretreated substrate indicated that the ethanol concentration and yield reached to 39.30 ± 0.57 g/L and 82.36 ± 1.15%, respectively. According to the results of lignin characterization, the aromatic rings in extracted lignin were opened forming dicarboxylic acids as well as derivatives due to the oxidation effect of chlorate, which is beneficial for its catalytic upgrading and composites preparation. Therefore, this study is important to valorization of lignocellulosic biomass.