Enhanced Degradation of Rhodamine B through Peroxymonosulfate Activated by a Metal Oxide/Carbon Nitride Composite

The development of high catalytic performance heterogeneous catalysts such as peroxymonosulfate (PMS) activators is important for the practical remediation of organic pollution caused by Rhodamine B (RhB). An economical and facile synthesized composite of copper-magnesium oxide and carbon nitride (CM/g-C3N4) was prepared by the sol-gel/high-temperature pyrolysis method to activate PMS for RhB degradation. CM/g-C3N4 exhibited a splendid structure for PMS activation, and the aggregation of copper-magnesium oxide was decreased when it was combined with carbon nitride. The introduction of magnesium oxide and carbon nitride increased the specific surface area and pore volume of CM/g-C3N4, providing more reaction sites. The low usage of CM/g-C3N4 (0.3 g/L) and PMS (1.0 mM) could rapidly degrade 99.88% of 10 mg/L RhB, and the RhB removal efficiency maintained 99.30% after five cycles, showing the superior catalytic performance and reusability of CM/g-C3N4. The synergistic effect of copper and g-C3N4 improved the PMS activation. According to the analyses of EPR and quenching experiments, SO4 center dot-, (OH)-O-center dot and O-2(center dot-) radicals and O-1(2) were generated in the activation of PMS, of which SO4 center dot- and O-1(2) were important for RhB removal. The toxicity of RhB was alleviated after being degraded by the CM/g-C3N4/PMS system. This study provides an efficient and promising strategy for removing dyes in water due to the hybrid reaction pathways in the CM/g-C3N4/PMS system.