Singlet oxygen dominated peroxymonosulfate activation by CuO-CeO2 for organic pollutants degradation: Performance and mechanism.

In this study, CuO-CeO2 was synthesized via an easy hydrothermal-calcination method and innovatively applied to peroxymonosulfate (PMS) activation for pollutants degradation under a non-radical oxidation pathway. Singlet oxygen (1O2) was the dominated reactive oxygen species in the CuO-CeO2/PMS system, leading to a dramatical degradation efficiency with Rhodamine B (RhB) as model compounds. The observed rate constant of the CuO-CeO2/PMS system was 7-11 times higher than that of only PMS, CeO2/PMS and CuO/PMS systems. Also, under the reaction conditions of 1.6 mM PMS, 0.4 g/L catalyst and initial pH 7, the degradation efficiencies of RhB, Methylene Blue, Reactive Blue 19 and atrazine were respectively up to 100%, 85.39%, 72.84% and 98.44% in 60 min. X-ray photoelectron microscopy analysis indicated that the electrons transfer between CuO and CeO2 and the formation of oxygen vacancy in CeO2 should be responsible for the enhanced 1O2 production, which involved a new non-radical oxidation pathway for PMS activation by CuO-CeO2 catalyst. Moreover, the combination of CuO and CeO2 increased reusability and stability of catalyst, allowing it remove more than 92% of RhB over a wide pH range (pH = 3-9). This study not only proved that CuO-CeO2 is an efficient and stable PMS activator but also provided a new insight into PMS activation through a non-radical oxidation pathway for organic contaminants removal from wastewater.