Treatment of chlorophenols in water matrix by UV/ferrioxalate system: Part I. Key process parameter evaluation by response surface methodology Original Research Article

The study was focused on the investigation of the feasibility of UV/ferrioxalate system for the degradation of para-chlophenol (p-CP) as a model wastewater pollutant. The influence of key process parameters was evaluated and the interactions between them were assessed using combined empirical/statistical approach applying Box–Behnken experimental design (BBD) combined with response surface methodology (RSM). BBD included three numerical and one categorical variables representing the key process parameters (initial pH, [Fe3+], [C2O42−] and type of UV irradiation). The quadratic RSM models predicting the rate of (p-CP) degradation by UV/ferrioxalate systems were developed. ANOVA was applied to evaluate the significance of models and modelsʹ components. On the bases of obtained statistical parameters (R2, F, p), developed RSM models are characterized as highly accurate and predictive. Additionally, it was determined that all four studied process parameters strongly influenced the UV/ferrioxalate system performance. The optimal conditions for maximal degradation of p-CP in water matrix by UV-C/ferrioxalate and UV-A/ferrioxalate are determined: pH0 = 4.4, [Fe3+] = 0.1 mM and [C2O42−] = 3.4 mM; and pH0 = 5.58, [Fe3+] = 1.38 mM and [C2O42−] = 8.16 mM. The optimal conditions strongly depended on the type of UV irradiation indicating the competitive degradation mechanisms of p-CP in water matrix including involvement of direct photolysis and radical species as well.