AbstractsChemistry

This work describes the fabrication of novel nanosilver/carbon nanotube polyamide thin-film composite (TFN) membranes by the interfacial polymerization of a thin polyamide layer containing nanosilver (nAg) particles over a polyethersulfone (PES) support containing either oxidised carbon nanotubes (CNTs) or nitrogen-doped carbon nanotubes (N-CNTs). Firstly, the CNTs and N-CNTs were prepared using a conventional floating catalyst chemical vapour deposition (FCCVD) method followed by acid treatment to achieve surface functionalisation or oxidation. The structure and surface functionalisation of CNTs and N-CNTs was studied using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy. N-CNTs were found to possess a typical bamboo-structure within their internal walls that is distinct from the hollow tubular morphology associated with undoped CNTs. The negatively charged surface functional groups such as –COOH, –OH and –C=O identified from FT-IR spectra of CNTs are essential for promoting hydrophilicity of the CNTs and to act as reactive sites for chemical bonding with PES support. The CNTs used in this work were of the multi-walled type. Moreover, the influence of the presence of oxidized CNTs or N-CNTs in the PES support membrane was studied. CNTs or N-CNTs (at dosages of 0.1 – 1.0 wt.%) were incorporated into the PES matrix via a phase inversion method to form CNT/PES or N-CNT/PES blend membranes. The PES blends were characterised using FT-IR spectroscopy, scanning electron microscopy (SEM) and contact angle analysis. An improvement in surface hydrophilicity upon the inclusion of CNTs in the PES blends was achieved (contact angle measurements). Furthermore, the presence of CNTs and N-CNTs at 0.1 wt.% dosage led to a reduction in macrovoids formed in the membrane sub-layer... Advisors/Committee Members: Nxumalo, E. N., Prof., Mhlanga, S. D., Prof (advisor).