A Staged Biorefinery of Moso Bamboo to Produce Fermentable Sugar, Furfural, and High-Quality Lignin by Integrating a Solvent and a Catalyst Deep Eutectic Solvent

An advanced deep eutectic solvent (DES) integrating a solvent and a catalyst, specifically tetrabutylammonium chloride and lactic acid, was proposed for the staged refinement of moso bamboo to produce fermentable sugars, furfural, and high-purity lignin. After pretreatment at 140 °C for 3 h, the sugar yield of the cellulose-rich pulp obtained reached 97.47%, which was significantly positively correlated to the removal of lignin (86.40%) and hemicellulose (76.72%). Deionized water was added to the pretreatment liquid to precipitate lignin, resulting in regenerated lignin with high purity (99.77%), regular-shaped submicrometer lignin particles (20–100 nm), and excellent antioxidant performance (83.09% inhibition percentage). The concentrated liquid was catalyzed by CuCl2·2H2O at 120 °C for 60 min, resulting in a furfural yield of 62.80%. Furthermore, the enzymatic hydrolysis efficiency remained 83.45–90.49% after four DES cycles. The system realizes full utilization of biomass components and provides a new strategy for green refining.