NSTI Nanotech 2009

Improved photocatalytic degradation of textile dye using titanium dioxide

A. Kar, Y.R. Smith, V. Subramanian
University Of Nevada, Reno, US

Keywords: textile dye, nanotubes

Abstract:

Dyes constitute a significant part of the waste produced in textile industries. These dyes pose environmental concerns and health hazard. Titanium dioxide (TiO2) is widely used for heterogeneous photocatalytic waste treatment. Several studies have reported the application of TiO2 slurry as well as immobilized TiO2 but they are limited by difficulties in post-treatment recovery and reduction in active surface area. The advantage of using TiO2 nanotubes as opposed to a particulate film includes efficient charge separation due to the absence of grain boundaries typical in particulate films. Recently we have demonstrated the photocatalytic degradation of a textile dye with TiO2 nanotubes that were prepared by anodization of titanium (Ti) foils [1].To increase the photoefficiency of the TiO2 nanotubes with respect to geometrical surface area we utilized Ti rods of diameter 0.5 mm for anodization. TiO2 nanotubes formed by anodization over Ti wires show a significant improvement in photocatalytic activity compared to the nanotubes formed over foils. Photodegradation experiments confirmed that anodized Ti rod shows 43 % Methyl orange (MO) degradation whereas anodized Ti foil shows 20 % MO degradation under the same conditions. Platinum (Pt) is known to assist in the photocatalytic degradation of the textile dyes. It functions as a sink for the photogenerated electrons and aids in electron-hole separation. Higher degradation rates with Pt-TiO2 nanotubes (Pt photodeposited onto TiO2 nanotubes) were observed. The higher photocatalytic activity over the anodized wires can be attributed to the efficient capture of reflected and refracted light by the radially outward oriented TiO2 nanotubes formed over the circumference of the titanium wire. The formation of TiO2 nanotubes over wires can be considered as an effective alternate to improve photodegradation rates by avoiding expensive additives. In a nut shell this work presents a comparative analysis of the photocatalytic activity of nanotubes formed over foils and wires by following the degradation of a textile dye, methyl orange.
 
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