Photocatalytic decomposition of textile dyes on TiO2-Tytanpol A11 and TiO2-Degussa P25

The present studies report on the results from the photocatalytic decomposition of organic dyes (Reactive Red 198 (RR198), Acid Black 1 (AB1) and Acid Blue 7 (AB7)), using two photocatalysts: TiO2-Tytanpol A11 and TiO2-Degussa P25 under UV/Vis illumination. All experiments were conducted with a constant amount of photocatalyst (0.2 g per 0.5 dm3 of dye solution), dye concentration (30 mg/dm3) and at constant pH (pH=2). The degree of dye decomposition in solution form the following order: RR198>AB1>AB7. The photodecomposition of the dyes on the photocatalyst surface was monitored by FTIR spectroscopy. Photocatalytic decomposition of the dyes takes place on the photocatalyst surface via intermediate by-products that are adsorbed on the surface with a higher intensity for A11 which exhibits lower activity. The results suggest that a surface reaction, where the dyes are adsorbed, is the controlling step of the process.