Characteristics and environmentally friendly extraction of cellulose nanofibrils from sugarcane bagasse

This study reports an environmentally friendly process to prepare cellulose nanofibrils (CNFs) from sugarcane bagasse (SCB), by ultrasonication combined with various mechanochemical pretreatments. The pretreatments included continuous steam explosion, dilute alkali-catalyzed (0.4 wt% NaOH) hydrothermal treatment, and bleaching with hydrogen peroxide. The morphology and physiochemical properties of the fibers obtained after each stage of treatment were characterized by various techniques. Suspensions of fibers subjected to different pretreatments were prepared by the same mechanical process. The result proved that continuous steam explosion pretreatment could strip the primary wall and the binding materials related to middle lamella, loosen the structure of fiber cell wall, and promote sequent nanofibrillation of the cellulose fibers. Therefore, the total energy consumption is reduced. The current pretreatments effectively removed non-cellulosic constituents of the raw fibers, using very small amount of chemical reagents. Individual CNFs typically had diameters of 20-40 nm, high aspect ratios, a fine web-like structure, and good thermal stability.