Synthesis of nanostructured titanium dioxide and application in water treatment

Abstract

Dyes that are released in the waste stream effluents from the textile industry have been reported as contributing factors to environmental problems. These dyes include methylene blue (MB) and methylene orange (MO) to mention a few organics which present a problem in water purification. Heterogeneous photocatalysis offers promise as a method that has been identified for water purification and remediation. Among many candidates as photocatalysts, titanium dioxide (Ti02) has been found to be the most suitable material for industrial use. This is due to its resistance to photocorrosion, low cost and low energy requirements in the photodegradation method. Though this photocatalyst has these promising characteristics, due to its small particle size and because it only covers 5% of the light absorption spectrum, it cannot perform at its peak. The purpose of this study was to obtain the optimum Ti02 loading deposited onto multi-walled carbon nanotubes (MWCNTs) as support materials. The study was also aimed at depositing silver (Ag) and palladium (Pd) onto Ti02/MWCNT in order to increase its photocatalytic efficiency for the degradation of MB dye. In this study, acid treatment of the support material, MWCNT, was conducted. Different Ti02 loadings deposited on MWCNT as well as noble metals deposited on MWCNT and Ti02IMWCNT supports were synthesized via the Metal organic chemical vapour deposition (MOCVD) method. Eleven catalysts, namely 10-40% Ti02IMWCNT (untreated), 20% Ti02IMWCNT (acid treated), 2% Ag-MWCNT, 2% Pd-MWCNT and 2% AglPd-MWCNT, 2% Ag-Ti02IMWCNT, 2% PdTi02IMWCNT and a novel 2% AglPd- Ti02IMWCNT were produced.