Synergistic multiple active species for the degradation of sulfamethoxazole by peroxymonosulfate in the presence of CuO@FeOx@Fe0

Abstract

In this study, bimetallic particles (CuO@FeOx@Fe0) were prepared by displacement plating and calcination to activate peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX). First, the key preparation parameters (i.e., theoretical Cu mass loading (TMLCu) and calcination temperature) of CuO@FeOx@Fe0 preparation were investigated by single-factor experiments. Then the properties of CuO@FeOx@Fe0 were analyzed by scanning electron microscope energy dispersive spectrometry (SEM-EDS), energy dispersive spectrometry mapping (EDS-mapping), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Subsequently, effects of PMS dosage, CuO@FeOx@Fe0 dosage and initial pH on the degradation of sulfamethoxazole were studied respectively. Meanwhile, the results of control experiments indicated that the initial SMX degradation efficiency of CuO@FeOx@Fe0 system was slower, but the final degradation rate was higher than that of Fe0/PMS system, which was due to the sustained release effect of Fe2+. In addition, the quantitative experiment of SO4− indicated that SO4− generated continuously in CuO@FeOx@Fe0/PMS system. Furthermore, the detection results of quenching tests and electron paramagnetic resonance (EPR) revealed the generation of multiple reactive oxygen species (i.e., SO4−, HO, O2−, 1O2) in CuO@FeOx@Fe0/PMS system, which degraded SMX synergistically. Finally, the SMX degradation pathways were proposed based on the intermediates detected by Liquid Chromatography-Quadrupole time of flight – Mass Spectrum (LC-QTOF-MS/MS) and the activation mechanism of CuO@FeOx@Fe0/PMS system was analyzed in detail. This study provided a new insight on the application of CuO@FeOx@Fe0 on organic pollutant degradation.