Advantages of ZIFs coated core-shell catalyst in activating persulfate to degrade antibiotics: Free radical identification and surface collision pathway mechanism

Abstract

Developing stable and efficient catalysts is a hot topic in the field of antibiotic remediation. In this study, we prepared Zs-Cu₂O, a composite material with an excellent synergistic effect of adsorption and catalytic oxidation, using the homogeneous diffusion method, which was used to activate peroxydisulfate (PS) to degrade OTC. In Zs-Cu₂O/PS system, Zn as an electron mediator promotes the electron transfer between Co and Cu, which makes Zs-Cu₂O have better performance and environmental adaptability. Through quenching experiments and EPR analysis, we clarified the synergistic mechanism of adsorption-catalytic oxidation. Our findings revealed the important roles played by electrostatic attraction, π-π bonds, reactive oxygen species (SO₄^•−、•OH、O₂^•− and ¹O₂), and Co(IV). At the same time, density functional theory (DFT) shows that Zs-Cu₂O has low adsorption energy, large charge transfer, strong PS cracking ability and excellent PS adsorption and activation performance. And it was found that the reaction followed a new surface collision oxidation pathway (SCOP), and no catalyst carrier was needed as an electron shuttle to mediate electron transfer. The degradation pathway and toxicity of OTC were evaluated, and a continuous flow reactor was constructed to evaluate its dynamic removal effect in water. This study not only offers a new approach for OTC pollution remediation but also paves the way for practical applications of ZIFs materials in the field of persulfate activation.