Performance and mechanism of co-doped Ce–Mn perovskite for degradation of tetracycline via heterogeneous photocatalysis coupled PMS oxidation

Abstract

In this work, CeMn1-xMxO3 (M = Cu, Fe and Co) perovskites were synthesized and used as efficient heterogeneous catalyst for degrade of tetracycline chloride (TC-HCl) via photocatalysis coupled peroxymonosulfate (PMS) oxidation under visible-light illumination. Metal doping significantly improved the catalytic activity of perovskites. The CeMn0.6Co0.4O3/PMS/Vis system demonstrated excellent performance that 96.4% of 60 mg/L of TC-HCl was degraded within 30 min with a high reaction rate constant of 0.136 min−1, which is about 4.3 times higher than that of CeMnO3, and almost 4.4 times higher than that of pure PMS. Results confirmed the addition of Co led to mixed valence states of Mn (III)/Mn (Ⅳ) and Co (II)/Co (III) in the perovskite structure, promoting the electron transfer from the CeMn0.6Co0.4O3 to PMS. Moreover, CeMn0.6Co0.4O3 exhibited good stability over a wide pH range (3.0–11.0). The rapid transformation of Co (II)/Co (III) redox pairs is critical for PMS activation as the limiting step. Superoxide radicals (•O2−), electron (e−) and sulfate radical (SO4−•) were the dominant oxidative species responsible for removing TC-HCl. This work proposed some new insights to understand the heterogeneous reaction mechanism during PMS oxidation and photocatalytic process and promote the development of perovskites catalyst for removal of organic pollutants.