Decolorization of azo dye containing wastewater using combined photocatalytic ozonation and Fe doped TiO₂ nanoparticles with RSM based optimization

This work is oriented on the photocatalytic ozonation of azo dye solution for its decolorization using UV light (UV/FeT/O 3 ) and solar light (solar/FeT/O 3 ). In this study Fe doped TiO 2 nanocatalyst (FeT) was prepared successfully in laboratory scale by molten salt method, was used as a catalyst during the treatment. For the optimization of process parameters, response surface methodology (RSM) is used in term of central composite design (CCD). Different operating parameter such as concentration of ozone, initial pH of solution, initial dye concentration of solution, dosing of FeT catalyst, and color reduction as a response of the process were inspected with a model development using CCD. ANOVA was also applied to statistically observation for the developed regression model. The developed CCD model was found statistically significant. This is confirmed by determination coefficient value (R 2 = 0.9778). The optimum color reduction 95.12 % for UV/FeT/O 3 was obtained at ozone concentration of 70 mgL −1 ; initial pH of 08; initial dye concentration of 200 mgL −1 ; catalyst dose of 1 gL −1 for 20 min of treatment process. A synergy index value of the UV photocatalytic ozonation process is 1.12, which indicates the rate between ozonation and photocatalysis. Kinetics is analyzed at two different concentrations of dye: 200 mg/L and 400 mg/L for both UV/FeT/O 3 and Solar/FeT/O 3 based treatment. First order reactions are observed for all experiments. Photocatalytic ozonation is cost-efficient than individual ozonation or individual photocatalysis.