Comprehensive utilization of poplar sawdust for glucose, xylose and lignin production using aluminum salt-based deep eutectic solvent

Deep eutectic solvents (DESs) demonstrate significant promise in biorefining because of their ability to break down the complex and resistant structure of lignocellulose. In this study, a ternary DES system composed of AlCl₃·6H₂O, formic acid (FA), and water was designed and applied for the pretreatment of poplar sawdust. The presence of AlCl₃·6H₂O and FA provides Lewis and Brønsted acid sites, respectively. The addition of water adjusts the acidity of the DES system, thereby increasing the separation efficiency of the three lignocellulose components. Under optimal conditions, DES (30 wt% water content) pretreatment achieved a high cellulose recovery rate of 91.3 %, with xylose yields and lignin recovery rates of 79.5 % and 90.1 %, respectively. Additionally, the cellulose residue achieved an enzymatic digestion efficiency of 97.9 %. The mass balance results revealed that the pretreatment strategy could utilize 77.6 % of the raw poplar sawdust, confirming that the method is economical and feasible. This DES pretreatment technique presents significant promise for biomass valorization.