Leveraging a Catalytic Alkaline Deep Eutectic Solvent for Mild Oxidative Fractionation of Lignocellulose

The high-value utilization of wheat straw, which is a major agricultural residue in China, is of significant importance. This study presents a mild and efficient process for the oxidative fractionation of wheat straw using a synergistic alkaline deep eutectic solvent (DES) combined with Fenton-like reagents (OH– + H2O2 + Fe2+). Under mild conditions (90 °C, 1 h), the process achieved 85.78% delignification while retaining 91.76% of the cellulose. Notably, the resulting pulp showed excellent digestibility, yielding 96.12% glucose and xylose with a very low cellulase loading (6 FPU of CTec3), which outperforms most state-of-the-art systems. Comprehensive investigations confirmed the critical role of alkaline DES and the enhancing effect of the Fenton-like reagents. Furthermore, the DES could be recycled ten times with only a minor reduction in fractionation efficiency. This work offers a promising strategy for the mild and sustainable biorefining of lignocellulosic biomass.