Effective photocatalytic decolorization of indigo carmine dye in Moroccan natural phosphate–TiO2 aqueous suspensions

• NP–TiO2 based on Moroccan natural phosphate (NP) doped by titanium dioxide TiO2 was tested as photocatalyst.
• NP–TiO2 catalyst was characterized by XRD, FTIR and surface area.
• Decolorization of indigo carmine (IC) dye in aqueous solution as a model pollutant under UV light.

Heterogeneous photocatalysis is a significant green technology for application in water purification. In this study, the photocatalytic activity of NP–TiO2 based on Moroccan natural phosphate (NP) doped by titanium dioxide TiO2 was evaluated by photocatalytic decolorization of indigo carmine (IC) dye in aqueous solution as a model pollutant under UV light. The NP–TiO2 catalyst was characterized by XRD, FTIR and surface area. The effect of the calcination temperature of NP–TiO2, catalyst concentration, initial concentration of the IC, initial pH, initial hydrogen peroxide H2O2 concentration and coexisting ions on the photocatalytic decolorization of IC was investigated. The NP–TiO2 showed a significantly higher rate of degradation of IC, when compared to TiO2. After 125 min of irradiation using a low intensity of UV-lamp (15 W ∗ 3 lamps = 45 W), 99% of IC solution (20 mg L−1) was decolorized with 0.5 g L−1 of the NP–TiO2 calcined at 600 °C at pH = 11. Therefore, this process can be developed as an economically feasible and environmentally friendly method to decolorize or treat dye wastewater using sunlight.