Photocatalytic degradation of azo dye in TiO2 suspended solution

The photocatalysis of azo dye, Orange G, by P-25 anatase TiO₂ was investigated in this research. The experiments were conducted in a batch reactor with TiO₂ powder suspension. Four near-UV lamps were used as the light source. The experimental variables included solution pH level, amount of TiO₂, illumination light intensity, and reaction time. A pseudo-first order reaction kinetic was proposed to simulate the photocatalytic degradation of Orange G in the batch reactor. More than 80% of 10 mg/L Orange G decomposition in 60-minute reaction time was observed in this study and fast decomposition of Orange G only occurred in the presence of both TiO₂ and suitable light energy. Faster degradation of Orange G was achieved under acid conditions. The degradation rates of Orange G at pH = 3.0 were about two times faster than those at pH = 7.0. Faster degradation of azo dye was observed for greater irradiated light intensity and more TiO present during the reaction. The reaction rates were proportional to TiO₂concentration and light intensity with the power order of 0.726 and 0.734, respectively.