In this study, the degradation and mineralization of aqueous solution containing a main carcinogenic pollutant, p-chloronitrobenzene (pCNB), were investigated by Fenton and photo-Fenton processes. Also the influence of operational parameters such as initial concentrations of H2O2, ferrous ion and pCNB has been studied on the removal of pCNB and chemical oxygen demand (COD). The pH was fixed at 3.00 in all experiments. The Box–Behnken design (BBD) of experiments and the response surface methodology were used to explore the influences of three independent variables on the response functions to get the optimal conditions. The analysis of variance tests were performed to determine the significance of the effects of independent variables on the response function. Different amounts of variables were optimized for the removal of pCNB and COD in both Fenton and photo-Fenton processes. At optimum conditions and after 20 min of reaction, the removal efficiency for pCNB was 98.5% and 100.0% in Fenton and photo-Fenton processes, respectively. The removal of COD in photo-Fenton process was more effective (91.4%) than Fenton process (58.5%) after 30 min of treatment. The Fenton process was powerful in the removal of pCNB, but it can remove the COD to some extent.
