Heterogeneous catalytic oxidation for the degradation of p -nitrophenol in aqueous solution by persulfate activated with CuFe 2 O 4 magnetic nano-particles

To evaluate the heterogeneous degradation of p-nitrophenol (PNP) in aqueous solution by catalytic oxidation process involving persulfate (PS) activated by CuFe2O4 magnetic nano-particles, the CuFe2O4/PS system was investigated in this study. CuFe2O4 magnetic nano-particles were synthesized with a sol-gel combustion method and then used as heterogeneous catalysts for PS activation. First, effects of CuFe2O4 dosage (0–40 g/L), PS dosage (0–10 mM), initial pH value (3.0–11.0) and co-existing inorganic ions on the degradation of PNP in aqueous solution by CuFe2O4/PS system were investigated comprehensively. In particular, the maximum PNP removal (89%) and total organic carbon (TOC) removal (81%) were obtained under the optimal conditions. Meanwhile, two control experiments (i.e., CuFe2O4 alone and PS alone systems) were carried out to confirm the performance in CuFe2O4/PS system. Furthermore, the reasonable PNP degradation pathway was proposed based on the intermediates detected by high performance liquid chromatography (HPLC). Finally, the mechanism of the CuFe2O4/PS system was proposed thoroughly according to the characterization of catalyst, the analysis results of metal leaching and radical scavenging studies. In a word, this study provides an effective oxidative system for PNP removal by CuFe2O4/PS heterogeneous process at ambient temperature.