According to some published papers, the typical hydrolysis methods, such as TEMPO-mediated oxidation and mechanical disintegration are popular in the preparation of CNF from various cellulosic feedstocks. Briefly, TEMPO process is initiated by (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, and the CNF obtained are more uniform and can be well dispersed in aqueous solution. In contrast, mechanically induced deconstructing strategies by different approaches (such as grinding, microfluidization, high-pressure homogenization, high-speed blending, refining, cryocrushing or ultrasonication) are considered as promising methods for isolating CNF. However, large-scale applications of these techniques have several restrictions. In fact, mechanical refining could efficiently separate the microfibrils, but the high crystalline ordered structure might be broken due to the lower selectivity of high shearing force, resulting in a lower crystallinity. Likewise, the TEMPO-oxidation process may turn some of the crystalline cellulose molecules into disordered structures during the oxidation and the resultant CNF product exhibited a lower CrI value, even compared to its starting material . Ultrasonication is another renowned way for CNF fabrication in which 20–50 kHz of ultrasound is applied to defibrillate cellulose for cell disruption. This is a greener hydrolysis technique as no chemical is involved during the generation of nanocellulose. The high frequency is generated and converted into the mechanical energy, which can be transmitted to cellulose via a metal probe. Unfortunately, the product obtained by this technique is a mixture of nano- and microfibers since some of the fibrils tended to be peeled off from the original cellulose fibers while some still remain on the surface of fibers . In addition, cellulose can be cycled through a high-pressure homogenizer to yield nanofibers. Typically, smaller and more uniform nanoparticles can be obtained with increasing number of homogenization cycles, but such high-pressure treatment is more likely to reduce and/or destroy the crystalline domains by separating the cellulose molecular mass, or instead fail to defibrillate the cellulosic pulp sufficiently . It is worth mentioning that the energy demand increases significantly with the increase of homogenizing time, and this may be the main drawback of application for CNF. The main issue often experienced by a homogenizer is extensive clogging and flocculation of the nozzle as the CNF tend to aggregate, and this means that extra capital cost is required to overcome this frequent issue. Therefore, some authors proposed that an additional pre- or post-treatment is necessary in order to obtain nanofibers product, such as hydrolysis, grinding, homogenization, or other mechanical treatments.