The long cellulosic fibrils were broken down to a great extent after the hydrolysis treatment catalyzed by Cr(NO3)3 and H2SO4, which can be clearly observed in the FESEM micrographs as presented in Figure 4b,c. Smaller and more individualized fragments were successfully disintegrated and/or separated from the bundles of micro-sized cellulose fibers, which resulted in further reduction of its diameter. These findings were in excellent accordance with the reported literature . The intermittent breakdown in the fibrillar structure of CNC in this study could be correlated with the successive hydrolysis treatment initiated by the Cr(NO3)3 metal salt and H2SO4 in the dissolution of the less-ordered defective crystalline regions as well as the hydrolytic cleavage of β-1,4-glycosidic linkages. The highly ordered crystalline arrangements appear in nanocellulose samples due to the formation of intra- and intermolecular H-bonding between the hydroxyl groups.