Photocatalytic Degradation of Methyl Orange: Influence of H₂O₂ in the TiO₂-Based System

The purpose of this study was to investigate the photocatalytic oxidation of a reactive azo dye. The photocatalytic activity of the TiO₂ was studied using a reactor equipped with UV-A sources, with maximum emission at 365 nm. The photocatalytic activity of the TiO₂ powder (99.9% anatase) and thin films has been measured through the decomposition of methyl orange solutions. The thin film was prepared by doctor blade and spray pyrolysis deposition (SPD). The TiO₂ suspensions were prepared at 1 g/L concentration, and the initial methyl orange concentration was fixed at 7.8125 mg/L. The influence of the TiO₂ (powder or thin films) and/or O₂ and H₂O₂ on the photobleaching rate, was tested under different experiments, at pH = 5. Thin films (doctor blade) of TiO₂ formed of mezo-sized aggregates formed of nanosized anatase crystallites show better photobleaching efficiency than thin film(SPD) due to their large internal surface. The rate is even higher in H₂O₂ compared to oxygen environment.