Cellulose nanofibers were isolated from banana peel bran using chemical treatment (CTdalkaline
treatment, bleaching, and acid hydrolysis) and enzymatic treatment (ETdalkaline treatment and hydrolysis
with xylanase). Both bran and cellulose nanofibers were characterized by size distribution, X-ray
diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR); the morphological features of the
bran and the nanostructures were studied by scanning (SEM) and transmission electron microscopy
(TEM), respectively. TEM analysis evidenced that both treatments effectively isolated banana fibers in the
nanometer scale. Nanofibers originating from CT and ET had an average diameter of 10.9 and 7.6 nm and
a length of 454.9 and 2889.7 nm, respectively. The aspect ratio of all the samples lay in the range of long
fibers. In neutral water, the nanofiber suspensions exhibited high and negative zeta potential, which
prevented the nanofibers from aggregating and yielded a more stable colloidal suspension. XRD studies
revealed that CT afforded more crystalline cellulose nanofibers (58.6%) as compared with ET (49.2%). FTIR
confirmed that the treatments removed most of the hemicelluloses and lignin present in the banana
fibers. Nanoparticles isolated from the banana peel by both treatments have potential application as
reinforcing elements in composites.