Unlocking dual lignin valorization from moso bamboo via ethylene glycol-tuned deep eutectic solvent fractionation

Lignin condensation and the recalcitrance of lignocellulose during conventional fractionation limit their valorization. Herein, we develop a tunable ternary deep eutectic solvent (TDES) composed of guanidine hydrochloride, lactic acid, and ethylene glycol for efficient fractionation of moso bamboo. By modulating the EG content, 74.3% delignification was achieved while preserving lignin structure, as confirmed by a β‑O‑4 content of 26.3/100 Ar (61.3% retention). Lignin nanoparticles self‑assembled into uniform lignin nanobottles (LNBs) with size controlled by lignin structure. Moreover, the preserved structural integrity enabled a high bio‑oil yield of 39.7 wt%. 4‑Vinylphenol was identified by Py‑GC/MS as the dominant product. Strong positive correlations were observed between β‑O‑4 content and both LNBs size and bio‑oil yield. Enzymatic saccharification of the treated residue achieved up to 94.4% glucose conversion. This work establishes a clear structure‑property relationship and presents a "structure‑first" strategy for dual‑pathway lignin valorization into nanomaterials and fuels.