Mechanism of persulfate activation with CuO for removing cephalexin and ofloxacin in water
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CuO was synthesized by a simple hydrothermal method and investigated as a heterogeneous activator of persulfate for the degradation of cephalexin and ofloxacin. X-ray photo-electron spectroscopy and hydrogen temperature-programmed reduction measurements reveal that CuO contains two types of Cu2+: one has more electron deficiency (named as Cu2+-h) and the other has relatively higher electron density (named as Cu2+-l). Electron paramagnetic resonance and radical scavenging experiments demonstrate that ·SO4− and ·O2− are responsible for the efficient degradation of cephalexin and ofloxacin, respectively. ·SO4− can be produced through the electron transfer from Cu2+-l to PS and the cleavage of peroxy bond, while ·O2− can be produced via the electron transfer from PS to Cu2+-h and the cleavage of S–O bond. Finally, the degradation intermediates were identified by liquid chromatograph–mass spectrometry. This study proposed a novel mechanism for the activation of persulfate with CuO, which is useful for the rational design of persulfate activator for controlling the production of active species.
KeywordsCuO Persulfate activation Active site Reactive species Pharmaceuticals Degradation
This work was supported by the Foundation for Distinguished Young Scientists of Hebei Province (No. B2018205153), and the Natural Science Foundation of Hebei Education Department (No. ZD2015114).
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Conflict of interest
All authors declare that they have no conflict of interest.