Alkaline deep eutectic solvent pretreatment of bamboo shoot shells for enhanced saccharification and downstream utilization of fractionated stream.

Abstract

Efficient pretreatment that enables selective fractionation, structural preservation, and coordinated downstream utilization remains a major challenge for lignocellulosic biorefineries. Herein, an alkaline deep eutectic solvent composed of triethylbenzylammonium chloride and ethanolamine was adopted for the integrated biorefinery of bamboo shoot shells. The pretreatment afforded 92.14-95.20 % delignification and 89.61-94.00 % hemicellulose removal across four feedstocks, while largely preserving cellulose integrity. Meanwhile, the recovered lignin retained substantial β-O-4 linkages, showed reduced condensation, narrowed molecular-weight distribution, and enhanced chemical reactivity, indicating its suitability for downstream valorization. Owing to the improved accessibility of the cellulose-rich residues, enzymatic hydrolysis delivered glucose yields of 92.06-96.70 % after 48 h. In addition to enzymatic saccharification, the fractionated components were further upgraded into lignin-containing cellulose nanofibrils, lignin nanoparticles, and nitrogen-doped carbon dots from the recovered spent solvent, demonstrating downstream utilization within one process. Overall, this work adopted an alkaline DES-based pretreatment strategy that integrates efficient fractionation, high enzymatic digestibility, and cascade valorization of major biomass components, demonstrating the potential of this strategy for integrated lignocellulosic biorefining.