Activation of peroxymonosulfate with CuCo2O4@kaolin for the efficient degradation of phenacetin

Abstract

CuCo2O4@kaolin was successfully synthesized by a sol-gel method and used as a heterogeneous catalyst to activate peroxymonosulfate (PMS) for the degradation of phenacetin (PNT). The results demonstrated that 10 mg/L PNT was completely decomposed by 1 mM PMS activated with 0.1 g/L CuCo2O4@kaolin within 15 min at initial pH 7. CuCo2O4@kaolin exhibited the best excellent catalytic performance among the tested catalysts, and the pseudo-first-order rate constants of PNT degradation were CuCo2O4@kaolin (0.40 min−1)>CuCo2O4 (0.22 min−1)>Co3O4@kaolin (0.10 min−1)>CuO@kaolin (0.08 min−1)>kaolin (0.02 min−1). CuCo2O4@kaolin also possessed superior stability, and the degradation efficiency of PNT declined from 100% in the first round to 80% in the fourth round. Nevertheless, a simple calcinating treatment (20 min) after the third round could restore its catalytic activity substantially and 95% removal of PNT was realized, 15% higher compared to without treatment. OH, SO4−, and 1O2 were the reactive oxygen species driving the PNT degradation. Based on the results mentioned above, characterizations of CuCo2O4@kaolin, and intermediates of PNT degradation, the possible pathways and underlying mechanisms of the PNT degradation in the CuCo2O4@kaolin/PMS system were deduced. CuCo2O4@kaolin/PMS had a universal degradation potential toward various organic pollutants, and the degradation efficiencies of sulfisoxazole, p-nitrophenol, chloramphenicol, and 2,4,6-Trichlorophenol reached 95–100% within 5–45 min. Thus, this work provides a novel and efficient PMS activator through an eco-friendly synthetic route, and it may be put into practice to degrade organic matter in wastewater.