5-Sulfosalicylic acid as an acid hydrotrope for the rapid and green fractionation of woody biomass

This study reported that 5-sulfosalicylic acid (5-SSA), a solid acid with hydrotropic properties, could efficiently and rapidly fractionate poplar biomass in an aqueous solution at mild conditions. The experimental results showed that 5-SSA-treatment could deconstruct the biomass recalcitrant intercellular structure and has excellent potential in lignin and hemicellulose dissolution and glucose release through subsequent enzymatic hydrolysis. Under the optimum conditions (80 wt% aqueous 5-SSA solution, 110 °C, and 60 min), a lignin removal rate of approximately 69.97%, cellulose recovery yield of more than 80.18% saccharification yield of 76.1% were achieved. 5-SSA acted as a catalyst to depolymerize lignin and hemicellulose by cleaving ether bonds and served as a solvent to dissolve lignin macromolecules by forming 5-SSA clusters and aggregates in water during fractionation. Density functional theory (DFT) indicated that strong H-bonding interactions between 5-SSA and lignin fragments contributed to the breakage of H-bonding network between lignin fragments.