Preparation of oxidized nanocellulose by using potassium dichromate

Nanocellulose derivatives are being used in a wide variety of high-quality functional applications. One of them is oxidized nanocellulose, which has been used in biomedical and pharmaceutical applications due to its biodegradable, biocompatible, hemostatic, and antibacterial properties. In this work, oxidized nanocellulose was synthesized using potassium dichromate as an oxidizing agent. The structure of oxidized nanocellulose was investigated by means of ultraviolet spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, and thermogravimetric analysis. The results showed that the primary hydroxyl groups of NC were selectively oxidized to carboxyl groups and their content of 1.36 mmol/g was achieved. The appearance of a new peak (1721 cm−1) in the FTIR- spectra related to the C=O group was observed. The change of oxidized nanocellulose’s crystal index from 88.0% to 82.5% was revealed, and the sizes of the unit cells of both nanocellulose and oxidized nanocellulose were calculated. The thermal stability of oxidized nanocellulose decreased compared to nanocellulose. The oxidation process of nanocellulose leads to a change in the shape and size of particles from acicular to spherical with a narrow particle size distribution. It was shown that oxidized nanocellulose has the ability to accumulate charges on its surface.