Application of response surface methodology on COD removal from textile wastewater by anodic chlorination and cathodic electro-Fenton process

This study applied response surface methodology to investigate chemical oxygen demand (COD) removal from dyeing wastewater by coupling anodic chlorination using Ti/Pt anode and cathodic electro-Fenton oxidation using activated carbon fiber cathode. The COD was removed by electrogenerated HOCl in the anodic compartment, while in the cathodic compartment the COD was removed by OH. produced by combing the cathodically generated H2O2 with Fe2+. A face-centered central composite experimental design was used to obtain the main variables, such as current density, initial chloride concentration, Fe2+ concentration and solution pH, on the individual response surface for anodic chlorination and cathodic electro-Fenton COD removal efficiencies. Two mathematical models that can describe the individual COD removal response were obtained. Analysis of variance showed a high coefficient of determination value (R-2) and insignificant lack of fit for both anodic and cathodic quadratic response surface models. The Pareto analysis gave the percentage effect of each variable on the response. For the anodic chlorination, the current density and the added chloride concentration were the most important two factors. On the other hand, the solution pH played the most important part for cathodic electro-Fenton oxidation.