Removal of organic dyes by UV/H₂O₂ process: Modelling and optimization

The effects of different operational parameters on the decolorization of a dye solution containing C.I. Acid Blue 92 (AB92) or C.I. Acid Black 1 (AB1) by the UV/H₂O₂ process were optimized using response surface methodology (RSM). The reaction time, dye and H₂O₂ initial concentrations and distance of the UV lamp from the solution were chosen as input variables. The removal process was performed according to a central composite design. Predicted results by the proposed models were in good agreement with experimental values (R² = 0.942 and 0.957 for AB92 and AB1, respectively). The optimum points were located by graphical response surfaces and contour plots. The removal process of the dyes was compared and the efficiency difference justified by considering the chemical structure of the dyes. Additionally, the electrical energy consumption and the related treatment costs were estimated employing the figure-of-merit electrical energy per order (E_EO).