Fractionation of herbaceous biomass using a recyclable hydrotropic p–toluenesulfonic acid (p–TsOH)/choline chloride (ChCl) solvent system at low temperatures

Abstract

Lignin valorization is significantly influenced by the degrees of lignin condensation measured by the amount of cleaved βeOe4 ether linkages and interunit CeC linkages formed during biomass fractionation. To minimize the cleavage of aryl ether and formation of CeC linkages, a p–toluenesulfonic acid (p–TsOH)/choline chloride (ChCl) solvent system with hydrotropic properties was evaluated. The ChCl was chosen to control the H⁺ concentration of the p–TsOH/ChCl solvent system. Compared with p–TsOH/H2O, the degradation of βeOe4 was kept in a similar rate during p–TsOH/ChCl fractionation; however, the formation of CeC linkage was slower. Under 75/25 p–TsOH/ChCl mass ratio at 80 °C for 20 min, 76.6 % of miscanthus lignin, with βeOe4 content of 30.9 %, and 88.9 % of wheat straw lignin, with βeOe4 content of 33.6 %, can be dissolved. In addition, the low polar and layered structure of hydrotropic p–TsOH/ChCl system has a strong ability to dissolve lignin, which resulted in lignin with larger particle size and lower surface charge. The results also indicated that lignin from p–TsOH/ChCl solvent system has great potential for lignin depolymerization to aromatics for valorization.

Citation

Wang, Wangxia; Gu, Feng; Zhu, J.Y.; Sun, Kaiyong; Cai, Zhaosheng; Yao, Shufeng; Wu, Wenjuan; Jin, Yongcan. 2020. Fractionation of herbaceous biomass using a recyclable hydrotropic p–toluenesulfonic acid (p–TsOH)/choline chloride (ChCl) solvent system at low temperatures. Industrial Crops and Products. 150: 112423. 8 p.