Carbocation Scavenger Assisted Diol Organosolv Pretreatment toward Efficient Biomass Saccharification and Lignin Valorization

Organosolv pretreatment effectively fractionates lignocellulosic biomass, producing high quality lignin. However, this pretreatment approach is still limited in achieving satisfactory cellulose hydrolysis and boosting lignin valorization. This work proposed a carbocation scavenger assisted diol organosolv pretreatment to address these challenges. As a result, 97.12% of cellulose could be converted to glucose after this sodium 2-naphthol-7-sulfonate (NS) assisted dilute acid-1,4-butanediol (DA-BDO) pretreatment and subsequent enzymatic hydrolysis. ATR-FTIR, GPC, 31P NMR, and 2D HSQC NMR analyses suggested the lignin repolymerization suppressing effect of BDO and the lignin depolymerization facilitating effect of NS, which probably resulted in the extensive delignification and significantly mitigated lignin inhibition on cellulose hydrolysis, accounting for the satisfactory cellulose hydrolysis. Meanwhile, the resultant DA-BDO-NS organosolv lignin (OL) was rich in phenolic hydroxyl groups with a low molecular weight, which was related to strong antioxidant and antibacterial activity. This work proposed possible mechanisms for the modified organosolv pretreatment in boosting enzymatic saccharification of softwood, while the lignin stream had great potential for value-added application for sustainable lignocellulosic biorefinery.