A novel type Ⅳ deep eutectic solvent for pretreating wheat straw to co-produce fermentable sugars and hydrophobic...

Deep eutectic solvents (DES), recognized as a green alternative to traditional solvents, have garnered increasing attention for lignocellulosic biomass pretreatment. While choline chloride remains the predominant hydrogen bond donor in DES formulations, this study introduces a series of metal salt-based DES system comprising aluminum chloride (AlCl₃) and polyols (ethylene glycol, glycerol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol) for wheat straw pretreatment. The optimized DES demonstrated exceptional efficiency in removing lignin (59.5-86.6 %) and hemicellulose (85.0-98.8 %), while preserving cellulose integrity (recovery > 90 %). Further, the enzymatic hydrolysis of glucan reached 94 % within 72 h, representing a fourfold improvement over untreated substrate. Concurrently, the regenerated lignin from the DES pretreatment exhibited a heterogeneous aggregates dominated by micro-nano particle structures. This lignin exhibited superior hydrophobicity (up to 5.93 L/g) and adsorption capacity for Rhodamine B (71.2 mg/g). This work establishes a sustainable strategy for simultaneous biomass valorization and functional material synthesis.