An ultrafast and green microwave-assisted ternary deep eutectic solvent biorefinery strategy for lignocellulose valorization through lignin extraction and lignin-containing cellulose nanofibers production

Herein a microwave-assisted ternary deep eutectic solvent (MW-TDES) pretreatment composed of choline chloride, maleic acid, and glycerol was developed for fractionation of biomass into cellulose-rich residue and lignin. Then the residue was upgraded to glucose by enzymatic hydrolysis and lignin-containing cellulose nanofibers (LCNFs). Under the optimal conditions (140 °C, 20 min), 87.5 % of cellulose was retained in the residue accompanied by 90.9 % delignification and 93.4 % hemicelluloses removal rate. A glucose yield of 82.5 % was achieved for the residue. Moreover, the pretreated residue was further ultrasonic treated to produce LCNFs with an average diameter of 19.8–25.4 nm. The LCNF films exhibited cellulose I β structure, good visible light transmittance, superior mechanical properties, high hydrophobicity and thermal stability. Additionally, the DES-isolated lignin showed low molecular weight ( M w , 1623–1486 g/mol), high purity (carbohydrate content, 0.13–4.12 %), and high antioxidant properties (IC50, 48–75 μg/mL). In short, the proposed MW-TDES treatment offers a sustainable route in converting biomass components into high-value products. • MW-TDES pretreatment achieved 87.5 % cellulose retention and 90.9 % delignification. • Glucose yield of 82.5 % was obtained at the optimal conditions. • LCNFs was produced via MW-TDES combined with ultrasonic treatment. • LCNF films showed high hydrophobicity, thermal stability, and mechanical properties. • DES-isolated lignin exhibited low M w , high purity, and strong antioxidant activity.