High-yield preparation of cellulose nanofiber by small quantity acid assisted milling in glycerol

A method was developed for the high-yield preparation of cellulose nanofibers (CNFs) using glycerol and a small quantity of sulfuric acid with a colloid milling mechanical dispersion. The glycerol together with a small quantity of sulfuric acid was employed to break hydrogen bonds between cellulose fibrils, after which the excessively swelled cellulose bundles could be easily disassembled to nanosize by a simple mechanical treatment. Reaction conditions, including the amount of sulfuric acid, the temperature and the preferred acid treatment time, were optimized to be 0.64% w/w sulfuric acid (based on the whole reaction system), 100 °C and 2 h respectively. Under the optimized conditions, CNFs with a width less than 100 nm and a length of several microns were obtained from various raw materials with high yield (above 85%), high crystallinity and an average degrees of polymerization (DP_v) of 200.