A novel ternary deep eutectic solvent pretreatment for the efficient separation and conversion of high-quality gutta-percha, value-added lignin and monosaccharide from Eucommia ulmoides seed shells.

A novel ternary deep eutectic solvent (DES), consisted of choline chloride, oxalic acid and ethylene glycol, was developed as a green, low-cost and recyclable pretreatment system for multi-stage utilization of Eucommia ulmoides seed shells. Under optimum conditions, 79.7 % hemicellulose and 65.6 % lignin were quickly removed while 84.0 % cellulose was retained. After DES pretreatment, the yield and purity of gutta-percha achieved 85.1 mg/g and 96.2 %, which increased 1.4 and 1.8 folds higher than that of un-treatment ones. Meanwhile, 69.1 % enzymatic digestibility of cellulose was obtained, that was 2.3 folds higher than that of raw substrates. Moreover, 53.6 % low-condensation lignin with aromatic structures and valuable aryl-ether linkages was well collected. Importantly, the DES that has been recycled five runs can still remove 73.9 % hemicellulose and 58.0 % lignin. Overall, the DES was determined to efficiently promote the separation and conversion of high-quality gutta-percha, value-added lignin and high-yield glucose from Eucommia ulmoides seed shells.