Heterogeneous photo catalytic degradation of anionic and cationic dyes over TiO2 and TiO2 doped with Mo6+ ions under solar light: Correlation of dye structure and its adsorptive tendency on the degradation rate

Degradation of synthetic dyes like Methyl Orange (MO), p-amino azo benzene (PAAB), Congo Red (CR), Brilliant Yellow (BY), Rhodamine-B (RB) and Methylene Blue (MB) under solar light were carried out using TiO2 doped with Mo6+ ions. The rate constant for the degradation of anionic dyes MO, PAAB, CR and BY was high at pH 5.6, while for cationic dyes the highest rate constant was obtained in the alkaline pH 8.0. These differences can be accounted to their adsorption capacity on the catalyst surface at different pH conditions. Among the photocatalyst used, Mo6+ (0.06%)–TiO2 showed enhanced activity due to the effective separation of charge carriers.