Photocatalytic degradation of some toxic analytical reagents with TiO <inf>2</inf>

Abstract

Photodegradation processes of two azo dyes at TiO2/H 2O interface under visible and ultraviolet light irradiation are investigated with different experimental techniques (absorption and fluorescence spectroscopy as well as total organic carbon analysis). Measuring their fluorescence spectra monitored the generation of some degradation intermediates. The photodegradation rate depends on dye structure and pH of the dispersion. The rate was found to be enhanced by increasing dissolved oxygen concentrations in the medium. The mechanism of the photodegradation process under uv-visible light illumination involves an electron excitation into the conduction band of the TiO2 semiconductor leading to the generation of very active oxygenated species that attack the dye molecules leading to photodegradation.