Sulfur-functionalized CoMn2O4 as a Fenton-like catalyst for the efficient rhodamine B degradation

Spinel-type bimetallic oxides have several potential applications in the catalytic degradation of organic wastewater due to their high catalytic activity and slow ion release rate caused by bimetallic synergy. In this study, sulfur-functionalized CoMn2O4 (S-CoMn2O4) was prepared as a Fenton-like catalyst by the sol–gel process, followed by calcination and sulfurization. The catalytic activity of CoMn2O4 was significantly increased by the incorporation of sulfur. The S-CoMn2O4(5.00%) catalyst modified with 5.00% sulfur in atomic percentage exhibited the best catalytic performance. Typically, 30 mg/L of rhodamine B was removed in 18 min by using 0.20 g/L S-CoMn2O4(5.00%) and 0.16 g/L peroxymonosulfate. Singlet oxygen and sulfate radicals are the primary active species, according to the trapping agent experiments and EPR measurements. The incorporation of sulfur leads to the formation of abundant oxygen vacancies in CoMn2O4 and sulfate groups bound on the surface of CoMn2O4, which promotes producing more active species. A synergism of Co and Mn ions in CoMn2O4 and high electron transfer mobility are also responsible for the enhanced degradation performance of S-CoMn2O4(5.00%). This study provides a feasible solution for improving cobalt manganese oxide as a more effective and long-lasting Fenton-like catalyst for the degradation of organic contaminants.