Response surface modeling for the treatment of methylene blue from aqueous media using electro-Fenton process before determination by UV-Vis spectrometer: Kinetic and degradation mechanism

In the present study, response surface methodology was employed to investigate the effects of main variables, including the initial MB concentration, hydrogen peroxide dosage, current density, and electrolysis time on the removal efficiency of MB using the electro-Fenton (EF) process. The MB concentration determination byU V-Vis spectrometer. The EF process degrades the MB contaminant molecules by the highly oxidizing species of the •OH. A quadratic regression model was developed to predict the removal of MB, where the R2 value was found to be 0.9970, which indicates the satisfactory accuracy of the proposed model. ANOVA analysis showed a non-significant lack of fit value (0.0840). Moreover, the predicted correlation coefficient values (R2=0.9915) were reasonably in agreement with the adjusted correlation coefficient value (R2=0.9958), demonstrating a highly significant model for MB dye removal. In addition, the obtained results showed 95.8% MB was removed in the optimum removal efficiency, including the initial MB concentration of 20 mg L-1, H2O2 dosage of 400 μL, and the current density of 7.0 mA cm-2, and electrolysis time of 10 min which was agreed with the predicted removal efficiency of 98.3%. Electrical energy consumption was found to be 0.163 kWh m-3. The constant rate value of Kapp at the optimum operating condition was 0.3753 min-1.