Removal of Oxidative Debris from Chemically Functionalized Multi-walled Carbon Nanotube (MWCNT)

Oxidized multi-walled carbon nanotubes (MWCNTs) were prepared by functionalizing MWCNTs with nitric acid (70%). In order to remove the oxidative debris, in which partially attached onto the outer layer of MWCNTs side wall, the functionalized MWCNTs (f-MWCNTs) by reflux method were carried out with NaOH (1M) and followed by HCl (1M) wash. The presence of the carboxyl (-COOH) group that covalently attached onto the f-MWCNTs side wall is confirmed with acid-base titration (Boehm titration). The transmission electron microscopy images show the comparison of pristine MWCNTs, f-MWCNTs and base-acid wash of f-MWCNTs, whereas energy dispersive Xray analysis confirms the removal of sulphur, a common catalyst material typically employed in the production of carbon nanotubes (CNTs). The UV-Visible spectroscopy shows the dispersibility of pure and functionalized MWCNTs in water (H2O).