Degradation of p-nitrophenol (PNP) in aqueous solution by Fe0-PM-PS system through response surface methodology (RSM)

Abstract

To develop a technology for the degradation of the toxic and refractory pollutants, the Fe0-PM-PS system and 6 control experiments were setup in this study. First, effects of Fe0 dosage (0–18.3g/L), PM dosage (0–25.0mmol/L), PS dosage (0–30.0mmol/L), initial pH value (3.0-11.0), air flow rate (0–2.0L/min), and feeding times of PM and PS (1–5) on the degradation of PNP in aqueous solution by the Fe0-PM-PS system were studied through the single-factor experiment. Furthermore, the optimized experimental conditions (i.e., Fe0 dosage of 11.9g/L, PM dosage of 15.0mmol/L, PS dosage of 18.1mmol/L and feeding times of oxidants of 4) were obtained through response surface methodology (RSM). The result shows that the maximum COD removal efficiency (89.0%) was obtained by the Fe0-PM-PS system under the optimal conditions, which was mainly attributed to the strong synergistic effect among Fe0, PM and PS. In addition, PNP degradation pathway was proposed according to the intermediates detected by HPLC. According to the analysis results of SEM-EDS, XRD and XPS, the reaction mechanism of the Fe0-PM-PS system has been clarified thoroughly. In short, these results suggest that the Fe0-PM-PS system should be proposed as an effective pretreatment process for the toxic and refractory PNP wastewater.