A multi-step sequential pretreatment for boosting biomass conversion

This study aims to overcome the structural recalcitrance of lignocellulosic biomass and improve the economic viability of biorefineries. A multi-step sequential pretreatment strategy combining hydrothermal pretreatment, twin-screw extrusion, and deep eutectic solvent (DES) treatments was developed to effectively deconstruct poplar biomass while recovering high-quality lignin, xylooligosaccharides (XOS), and fermentable sugars.The results demonstrated that this integrated approach achieved exceptional pretreatment performance, with 89.7% delignification and 85.3% xylan removal. The strategy enabled near-complete cellulose enzymatic hydrolysis at a low enzyme loading (15 FPU/g) and achieved a 45.7% XOS yield. Furthermore, the process yielded high-purity lignin (99.9%) with an 81.5% recovery rate,characterized by reduced molecular weight, enhanced antioxidant activity (IC₅₀ = 56.16 mg/L), and a high phenolic hydroxyl content (2.81 mmol/g).This sequential pretreatment strategy exhibits significant potential for the integrated valorization of poplar biomass into fermentable monosaccharides, functional oligosaccharides, and antioxidant lignin derivatives, advancing the sustainability of lignocellulosic biorefineries.