Catalytic oxidation of reactive blue 222 dye using peroxymonosulfate activated by Mn3O4: Parameter optimization using response surface methodology

In the present study, the Mn3O4 nanoparticles (Mn3O4 NPs) were synthesized for peroxymonosulfate (PMS) activation to remove reactive blue 222 (RB 222), COD and TOC. The structure of the NPs was characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) techniques. Moreover, central composite design (CCD) was used to investigate the operating parameters affecting the decolorization process such as Mn3O4 dosage, PMS and dye concentration, and pH, as well as the optimization of them. Accordingly, P-value = 0.01, lack of fit = 0.18, and Prob > F = 3.09 illustrated that the model was capable of predicting the responses of RB222 decolorization efficiency. Under the optimal conditions: Mn3O4 dosage = 0.15 g/L, PMS concentration = 0.75 g/L, initial dye concentration = 65 mg/L, and pH = 5 at a fixed time of 5 min, the decolorization efficiency rate was 92.00%. It was found that the excellent performance of the PMS/ Mn3O4 process was attributed to the synergistic effects of Mn3O4 and PMS.