High Carboxyl Content Cellulose Nanofibers from Banana Peel via One-Pot Nitro-Oxidative Fabrication

Abstract

Banana peels (BP) are the outer covering of a banana fruit and are usually discarded as abundant and underutilized waste from banana production and consumption. This work investigated the bioresource for one-pot preparation of carboxyl cellulose nanofibers (CCNF) using the nitro-oxidation method. Briefly, BP was added to a mixture of HNO3 and NaNO2 at 30-50oC for 6 h. To characterize the obtained material, different methods, including X-ray diffraction, TEM images, FTIR spectroscopy, EDX spectroscopy, and acid-base titration, were used. TEM images reveal that the nanofibers were mainly formed with a diameter of roughly 20-50 nm. Moreover, the results of FTIR, EDX, and titration proved the formation of carboxylic acid (-COOH) groups in CCNF with an amount of 4.9 mmol/g, or 22 wt%. This high carboxyl content makes CCNF an ion-exchange material, thereby enabling the development of new applications. Compared with traditional multistep processes for the preparation of cellulose nanomaterials, the current approach is simpler, uses fewer chemicals, and consumes less energy. Overall, these successful results not only valorize potential banana peel waste but also introduce an advanced material for further use.