Green, one-pot biomass hierarchical utilization strategy for lignin-containing cellulose nanofibrils and fractionated lignin preparation

The recalcitrant nature of plant cells makes biomass hierarchical utilization challenging. Here we report a green, one-pot strategy to achieve fractionation of sugarcane pith cellulose and lignin. Lignin-containing cellulose nanofibrils (LCNFs) and fractionated lignin (by tailored choline chloride and oxalic acid-based deep eutectic solvents (DESs) and ultrasonic nanofibrillation pretreatments) were studied. The obtained LCNFs had a well-independent structure and uniform size distribution (5.05–6.88 nm in diameter). Lignin fractionated by diol acid DES (DADES) exhibited a relatively homogeneous molecular weight (Mw, 2013–2827 g/mol), reduced lignin heterogeneity, and condensation under acidic conditions. Besides, multi-functional LCNF papers were prepared by vacuum filtration of their suspensions and had excellent bio-disintegration capability, water resistance, UV-shielding performance, and thermal stability. This study demonstrated that DADES enables hierarchical biomass utilization and successful production of high-value-added building blocks, such as LCNF and fractionated lignin.