Effect of Reaction Time on Modification of Multi-walled Carbon Nanotubes with HNO3

The functionalization of Multi-walled Carbon Nanotubes (MWCNTs) is addressed to improve its interaction capability with other materials for further applications. The oxidation of MWCNTs by nitric acid is one of the promising methods for its surface modifications. In this research, MWCNTs functionalization was carried out in several steps such as oxidation, filtration, washing, and drying. The optimization of reaction time for MWCNTs functionalization was conducted to achieve the optimum condition which efficiently functionalizes MWCNTs surface. The sample characterizations were investigated by Boehm titration, Fourier Transform Infrared (FTIR) Spectroscopy, Thermo Gravimetric Analysis (TGA), and dispersion test. As a result, carboxyl groups were successfully attached onto the MWCNTs surface and stable dispersion of MWCNTs was obtained after 12 hours. Oxidation with nitric acid for 12 hours at room temperature is the optimum treatment time for surface modification.