Oxygen vacancy concentration modulation of perovskite-based heterogeneous catalysts for Fenton-like oxidation of tetracycline

Oxygen vacancies (VO) constructing in metallic compounds have been verified to enhance hydrogen peroxide (H2O2) activation for pollutants treatment. However, the interactions between surface VO concentration and H2O2 were still ambiguous. In this study, perovskites with different surface VO concentration were successfully prepared by a simple sol-gel process. Experimental results showed that A-site cation deficient was capable of distorting FeO6 octahedra in Ca1−xFeO3-δ (x = 0, 0.1, 0.2) orthorhombic perovskites for the regulation of surface VO concentration. Afterwards, Ca0.9FeO3-δ exhibited excellent catalytic activity and stability for tetracycline (TC) degradation, which was 4 times higher of catalytic enhancement than that of the raw Ca1.0FeO3-δ. Moreover, up to 9, 17 and 27 times of catalytic enhancement as compared with commercial Fe3O4, ɑ-FeOOH and Fe2O3 towards TC degradation. Based on electron spin resonance and free radical quenching experiments, the hydroxyl radical (∙OH) was the main active species for the catalytic degradation of TC. Meanwhile, higher or lower surface VO concentration was harmful to the production of ∙OH. Additionally, the toxicity of TC degradation by-products exhibited a decreasing trend according to the results of toxicological simulation. This work provides a new strategy for designing an efficient and promising heterogeneous Fenton-likes catalyst for environmental remediation.