Application of central composite design for the optimization of photo-destruction of a textile dye using UV/S₂O₈ ^2- process

The photooxidative destruction of C. I. Basic Red 46 (BR46) by UV/S ₂O₈^2- process is presented. Central Composite Design (CCD) was employed to optimize the effects of operational parameters on the photooxidative destruction efficiency. The variables investigated were the initial dye and S₂O₈^2- concentrations, reaction time and distance of the solution from UV lamp. The predicted values of the photodestruction efficiency were found to be in good agreement with the experimental values (R² = 0.9810, Adjusted R² = 0.9643). The results of the optimization predicted by the model showed that the maximum decolorization efficiency (>98%) was achieved at the optimum conditions of the reaction time 10 min, initial dye concentration 10 mg/l, initial peroxydisulfate concentration 1.5 mmol/l and distance of UV lamp from the solution 6 cm. The figure-of-merit electrical energy per order (E_Eo) was employed to estimate the electrical energy consumption and related treatment costs.