Facilitating lignocellulose fractionation of Moringa oleifera Lam. husk by pretreatment with a novel 1-tetradecyl-3-carboxymethylimidazolium bromide-based deep eutectic solvent

Abstract

Refining lignocellulose into fermentable monosaccharides remains a challenging endeavor. In this study, we employed a novel deep eutectic solvent (DES) composed of 1-tetradecyl-3-carboxymethylimidazolium bromide (C₁₄CIMBr) and lactic acid (LA) for the pretreatment of Moringa oleifera Lam. husk (M. oleifera husk), aiming to enhance lignocellulose fractionation. The optimal conditions identified were 165°C, 43.9 minutes, and a molar ratio of C₁₄CIMBr to LA at 1:4.8, resulting in the removal of 93.8% of lignin and 96.8% of hemicellulose. Following enzymatic hydrolysis of the pretreated M. oleifera husk, yields of glucose and xylose reached 94.3% and 86.1%, respectively, representing significant increases by factors of 7.0-fold and 10.3-fold compared to untreated M. oleifera husk. Molecular simulations indicated that the novel DES effectively disrupts the original internal hydrogen bonding network while reconstructing new DES-lignocellulosic hydrogen bonds, it also demonstrates excellent solubilization capabilities for lignin cleavage products. Finally, the yield of regenerated lignin reached 81.3%, exhibiting notable bactericidal activity under blue light irradiation.