Spray-flame synthesis of LaCo0.2Mn0.8O3 for selective peroxymonosulfate activation into singlet oxygen towards efficient degradation of carbamazepine

Abstract

Improving the efficiency and stability of heterogeneous catalysts is essential for effectively utilizing peroxymonosulfate activation in industrial wastewater treatment. Perovskite ABO₃ catalysts with high structural flexibility have gained considerable attention in the peroxymonosulfate activation for the removal of hazardous organic compounds from wastewater. However, there is still considerable potential for catalytic enhancement due to the ease of tailoring its composition and structure. Herein, we introduce a scalable method to synthesize LaCo_0.2Mn_0.8O₃ with the aim of improving the catalytic performance. Interestingly, LaCo_0.2Mn_0.8O₃ with abundant oxygen vacancies and improved dispersion stability exhibited enhanced catalytic degradation of carbamazepine compared to the LaMnO₃ and LaCoO₃ catalysts in the peroxymonosulfate activation system. The partial substitution of manganese by cobalt in LaMnO₃ leading to the LaCo_0.2Mn_0.8O₃+peroxymonosulfate system maintains a relatively high performance over repeated usage. Furthermore, the LaCo_0.2Mn_0.8O₃ catalyst exhibited excellent catalytic performance and stability across a broad pH range (3–9). Electron paramagnetic resonance and radical quenching experiment tests demonstrated singlet oxygen (¹O₂) as the primary active species for carbamazepine degradation in the LaCo_0.2Mn_0.8O₃+ peroxymonosulfate system, while free radicals, such as sulfate radicals (⁠SO₄^•–), hydroxyl radicals (^•OH), and superoxide radicals (O₂^•–), played a minor role in the carbamazepine removal. Taken together, this research provides significant insight into the effect of B-site substitution on the catalytic performance of perovskite catalysts.