A novel recyclable alkaline deep eutectic solvent for enhanced biomass fractionation and enzymatic hydrolysis

• A novel alkaline DES was synthesized by NH 4 Cl and monoethanolamine. • Alkaline DES promoted delignification (95%) and carbohydrate retention. • Glucose and xylose yields were up to 96% in only 24 h of enzymatic hydrolysis. • The recovered alkaline DES showed excellent recyclability. Effective lignin removal while preserving carbohydrates is a critical challenge in the production of bioethanol. Herein, a novel alkaline deep eutectic solvent (DES) composed of ammonium chloride (NH₄Cl) and monoethanolamine (MEA), was designed for efficient lignin removal and carbohydrate retention in corn stalks pretreatment. Under optimal conditions (MEA/NH₄Cl with a molar ratio 6:1, 140 °C, 6 h), the DES achieved 95.7% lignin removal, with glucose and xylose yields after enzymatic hydrolysis of the residue reaching 98%. Remarkably, glucose and xylose yields were up to 96% within only 24 h, cutting the reaction time by two-thirds compared to the conventional 72 h industrial process and significantly enhancing efficiency. The DES also maintained high efficiency after five reuse cycles, demonstrating excellent recyclability and economic potential. Structural analysis revealed increased crystallinity and porosity, providing mechanistic insights into enhanced enzymatic accessibility. This work establishes a sustainable and innovative strategy for lignocellulose pretreatment, paving the way for cellulosic bioethanol production. A novel recyclable alkaline deep eutectic solvent pretreatment for efficient lignocellulose fractionation and enzymatic hydrolysis.