Synergistic pretreatment of sorghum straw using a three-component deep eutectic solvent benzyltrimethylammonium...

This study focuses on the effective pretreatment of waste sorghum straw (SS), aiming to elevate its enzymolysis efficiency by increasing the separation of xylan and lignin and promoting the accessibility of cellulose. An efficient co-production of xylo-oligosaccharide (XOS) and reducing sugars was realized. Ternary eutectic solvents (TDES) fabricated with benzyltrimethylammonium chloride (BTMAC), oxalic acid (OA), and lactic acid (LA) have shown great potential in the pretreatment of lignocellulose biomass. This study systematically investigated the pretreatment effect of BTMAC/OA/LA (OL-DES) under the optimal pretreatment conditions of 120 °C for 40 min and SS with a molar ratio of DES 1:2:1. OL-DES system significantly improved the removal efficiency of lignin and xylan, acquiring 91.0% of delignification and 88.4% of xylan removal. Furthermore, the hemicellulose component of SS can be efficiently converted into XOS (2.6 g/L). After OL-DES pretreatment, the enzymolysis efficiency was approximately 4.25-fold higher than that of raw materials. The accessibility of cellulose significantly increased from 269.4 to 592.2 mg/g. Through molecular simulation methods such as Kamlet-Taft parameter analysis, electrostatic potential calculation and independent gradient model (IGM) analysis, the hydrogen bond interaction and electrostatic complementarity mechanism between OL-DES components and lignocellulose components were revealed, providing a theoretical basis at the molecular level for understanding DES-mediated biomass deconstruction. Mass and energy flow analysis showcased that this pretreatment process achieved efficient recovery and conversion of carbohydrate resources. This work provided a green and efficient pretreatment strategy for the high-value utilization of lignocellulose biomass, which has broad application prospects in the field of biorefining.