Eco-efficient fractionation of bamboo using a pyruvic acid-based deep eutectic solvent: a waste-minimized strategy for comprehensive valorization

Abstract

Achieving comprehensive biomass valorization with minimal environmental impact is a critical challenge in advancing sustainable biorefineries. This study establishes a waste-minimized strategy for bamboo fractionation using a novel deep eutectic solvent (choline chloride/pyruvic acid), designed to enhance pyrolytic saccharification efficiency, lignin valorization, and direct spent-filtrate upcycling. Under mild conditions (100 °C, 1 h), this eco-efficient pretreatment facilitated selective delignification (98%) while retaining 92% of cellulose. The fractionated residue was converted to levoglucosan (36% yield) via fast pyrolysis, and the extracted reactive lignin was successfully applied in UV-protective sunscreens and aromatic chemical production. Notably, the xylose-enriched spent DES filtrate was directly incorporated into polyvinyl alcohol (PVA) as a proof-of-concept additive to prepare composite films, thereby avoiding direct discharge or energy-intensive purification of this organic-rich stream. While these films exhibited enhanced mechanical and UV-shielding properties, their water sensitivity makes the current formulation most suitable for dry applications. Overall, this work presents a waste-minimized bamboo biorefinery strategy that integrates biomass fractionation, component valorization, and spent-liquor upcycling within a cleaner-production framework.