Photooxidative decolorization of two organic dyes with different chemical structures by UV/H2O2 process: Experimental design Original Research Article

The present work deals with the application of Response Surface Methodology (RSM) to study the effects of operational parameters on the photooxidative decolorization of two dyes (C.I. Basic Blue 3 (BB3) and C.I. Acid Green 25 (AG25)) with different molecular structure under UV light illumination (30 W) in the presence of hydrogen peroxide (H2O2). The variables investigated were the reaction time, dye and H2O2 initial concentrations and distance of UV lamp from the solution. Central Composite Design (CCD) was used for the optimization of photooxidative decolorization process. Predicted values were found to be in good agreement with experimental values (R2 = 98.43 and 95.06 and Adj–R2 = 97.05 and 90.74 for BB3 and AG25, respectively), which indicated suitability of the model and the success of CCD in optimization of UV/H2O2 process. Graphical response surface and contour plots were used to locate the optimum points. The photooxidative removal of the dyes in the optimal conditions was compared and a structure-degradability relationship was established. Moreover, the figure-of-merit electrical energy per order (EEO) was employed to estimate the electrical energy consumption.