Photocatalytic oxidation of methyl orange in presence of titanium dioxide in aqueous suspension. Part I: Parametric study

The photocatalytic oxidation of a mono azo dye methyl-orange (C14H14N3SO3Na) dye has been investigated in TiO2/UV aqueous suspensions irradiated by artificial UV-light until its complete mineralization was achieved. It was found that there was no degradation for the MeO in the dark and in the presence of TiO2. The dependence of dye photobleaching rate on the following parameters: (i) substrate concentration; (ii) catalyst amount; and (iii) pH was performed to optimize the experimental parameters. Varieties of commercial TiO2 catalysts using several crystalline were tested to compare their photoactivity. As a result, it was found that the efficiency of the process strongly depends on the working conditions. The highest degradation rate of MeO was obtained at optimum parameters such as: dosage TiO2 (0.8 g/L), initial pH (3) and low dye concentration (≤ 50 mg/L), using Degussa P25 as photocatalyst.