A ternary deep eutectic solvent for efficient biomass fractionation and lignin stabilization.

The efficient isolation and lignin stabilization are critical to the fractionation process of lignocellulosic biomass, enabling the subsequent valorization of both carbohydrates and lignin. In this study, a ternary deep eutectic solvent pretreatment system with outstanding reusability has been developed. Under optimal conditions (ChCl: MT: p-TsOH = 1:1:0.5, 120 °C, 60 min), the system efficiently removed 94.66 % of hemicellulose and 95.74 % of lignin while retaining 84.50 % of cellulose. Glucose was obtained from the cellulose-rich solid residue via enzymatic hydrolysis, achieving an 87.12 % yield. This DES system inhibits lignin condensation through a dual mechanism of α-etherification and intermolecular forces (π-π stacking and hydrophobic interaction). The recovered lignin exhibits a low molecular weight (922-1049 g/mol), high phenolic hydroxyl content (2.57-3.37 mmol/g), low polydispersity (1.54-1.61), and high purity (93.02 %). Combined with its superior antioxidant activity and UV shielding properties, this lignin represents a promising new resource with potential applications.