Coupled Mechano‐Chemical Pretreatment of Poplar Wood to Enhance Enzymatic Hydrolysis for Low‐Cost Biorefinery

ABSTRACT Common methods of lignocellulose pretreatment (such as acid method, alkali method, and organic solvent method) have been severely restricted in their development due to issues such as harsh reaction conditions, high cost of reagents, and heavy environmental burden. Herein, this work developed a coupled pretreatment process combining alkali impregnation, steam softening, and twin‐screw extrusion with ammonium sulfite cooking. By incorporating alkali leaching and steam softening, this method reduces the energy required to break down the degradation barriers of lignocellulose. The results show that under the optimal pretreatment conditions (2.5 wt% ammonium sulfite, 165°C, 1 h), lignin can be effectively removed, and the relative content of cellulose in the solid residue increased to 53.68%, with a cellulose retention rate as high as 97.51%. Although the enzymatic saccharification rate of the 96 solid residue (78.42%) was slightly lower than that of methods using expensive solvents or strict conditions, its sugar production cost of $0.85 kg −1 was lower than that of the traditional acid method, organic solvent method, and ionic liquid method. In summary, this study has established a technological foundation for overcoming the difficulty of breaking the dense structure of forest biomass through the synergistic effect of pretreatment.