Synergistic effects of sodium methoxide and glycerol pretreatment on wheat straw for efficient enzymatic...

Efficient pretreatment under mild conditions is critical for reducing lignocellulosic recalcitrance while maintaining high sugar yields on a raw biomass basis. In this study, a synergistic sodium methoxide (CH₃ONa)-glycerol pretreatment was systematically investigated and optimized for wheat straw to maximize reducing sugar production. The effects of key pretreatment parameters, including CH₃ONa concentration, pretreatment temperature, and pretreatment time, were first examined through single-factor experiments and subsequently optimized using response surface methodology. Under the optimized conditions (1.24-1.25% CH₃ONa, ∼ 124 °C, 60 min), the pretreated wheat straw achieved a high total reducing sugar concentration of 17.64 g L^-1 and a high total reducing sugar yield of 0.4927 g g^-1 raw material, underscoring the importance of yield-based evaluation that integrates enzymatic digestibility with solid recovery. Comprehensive structural and physicochemical analyses, including scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry, revealed that the CH₃ONa-glycerol system selectively removed hemicellulose and lignin while preserving the native cellulose I crystalline structure. The enhanced enzymatic saccharification performance is attributed to effective matrix deconstruction and improved cellulose accessibility, which outweighs the increase in crystallinity caused by the preferential removal of amorphous components. Overall, these findings demonstrate that CH₃ONa-glycerol pretreatment represents an effective, synergistic, and yield-oriented strategy for enhancing enzymatic saccharification of wheat straw under relatively mild conditions, demonstrating strong potential for lignocellulosic biorefinery applications.