Electro-Fenton oxidation of coking wastewater: optimization using the combination of central composite design and convex optimization method.

The electro-Fenton treatment of coking wastewater was evaluated experimentally in a batch electrochemical reactor. Based on central composite design coupled with response surface methodology, a regression quadratic equation was developed to model the total organic carbon (TOC) removal efficiency. This model was further proved to accurately predict the optimization of process variables by means of analysis of variance. With the aid of the convex optimization method, which is a global optimization method, the optimal parameters were determined as current density of 30.9 mA/cm2 , Fe2+ concentration of 0.35 mg/L, and pH of 4.05. Under the optimized conditions, the corresponding TOC removal efficiency was up to 73.8%. The maximum TOC removal efficiency achieved can be further confirmed by the results of gas chromatography-mass spectrum analysis.