Oxygen-vacancy-rich CeO2/LaFeO3 for peroxymonosulfate activation: Singlet oxygen as the main active oxygen to degrade organic pollutants in high-salinity environments

Abstract

Due to the quenching effect of typical anions on free radicals, free radical based advanced oxidation processes have always been difficult to effectively treat high-salinity organic wastewater. In this work, an oxygen-vacancy-rich ceria-perovskite composite (CeO2/LaFeO3) was successfully prepared, and the oxygen vacancy became the active sites for activating peroxomonosulfate to produce a large amount of singlet oxygen (1O2) as the main reactive oxygen species (ROS) for tetracycline degradation in high-salinity organic wastewater. In the typical high-salinity environments (30000–70000 mg·L−1, NaCl, Na2SO4, NaNO3, Na2CO3, NaH2PO4, or NaBr), CeO2/LaFeO3 can achieve more than 95 % removal of TC within 40 min, and the 40 min removal rate of TC in a variety of mixed salt environments is also maintained above 94 %. Common cations (K+, Fe3+, Mn2+, Ca2+, Mg2+, Cu2+, and Ba2+) were also not found to have a significant negative effect on TC removal. CeO2/LaFeO3 can completely remove TC within 40 min in 5 cycles, the granular CeO2/LaFeO3 immobilized in a self-made small device can also achieve continuous removal of more than 96.6 % of TC within 420 min. The results of pea seed germination test showed that CeO2/LaFeO3 as catalyst for heterogeneous water treatment would not bring additional environmental risks.