A simple procedure to quantitatively assess the photoactivity of titanium dioxide films

A simple and inexpensive procedure based on the bleaching of orange II (acid orange 7) solution has been developed in order to quantitatively assess the photocatalytic activity of titanium dioxide thin films. The influence of experimental parameters including, pH and light flux density on the reaction rate has been investigated. The results of this study suggest that at natural pH (7.2) and low dye concentration, the mechanism responsible for the degradation of orange II is mainly photooxidation via the formation of radicals. The procedure was used to compare the photoefficiency of TiO2 films poisoned with variable amounts of sodium. The obtained results are in good agreement with the previously reported effect of sodium on the photoactivity of titanium dioxide thin films.