Enhanced Enzymatic Hydrolysis of Tobacco Stalk via Simultaneous Deconstruction and Modification through Triton X-100-mediated Organosolv Pretreatment.

Tobacco stalks (TS) present substantial potential for biofuel and biochemical production; however, their complex lignin structures and tightly bound carbohydrates pose significant challenges for enzymatic hydrolysis due to high recalcitrance. This study explores Triton-X 100-mediated 1,4-butanediol combined with AlCl3 pretreatment for TS fractionation towards improving enzymatic hydrolysis. Optimized pretreatment conditions achieved a significant removal of 87.8% of hemicellulose and 81.0% of lignin while maintaining a high cellulose retention of 90.1%. Subsequently, the pretreated biomass recorded 91.2% glucose yield after enzymatic hydrolysis at 10% w/w solid with 12 FPU/g enzyme loadings, substantially outperforming controls. The presence of Triton-X 100 in pretreatment reduced enzyme requirements by up to 33.3%. Structural characterization of the pretreated TS indicated effective disruption of lignin-carbohydrate complexes and an increase in biomass porosity by 1.2-2.3 folds, contributing to improved cellulose accessibility and enzymatic hydrolysis efficiency. Moreover, structural characterization of lignin revealed that Triton-X 100 grafted onto lignin by etherification, yielding a 21% reduction in phenolic hydroxyl content and enhancing surface negative charge. These modifications effectively weaken both hydrogen bonding and electrostatic interactions between lignin and cellulase, thereby improving enzymatic hydrolysis efficiency. Overall, the proposed pretreatment presents a promising strategy for efficient fractionation and hydrolysis of TS biomass.