Performance and Mechanism of Brucite/g-C3N4 Catalyst-Activated Peroxymonosulfate for Rapid Degradation of Methylene Blue

The escalating utilization of dyes and the subsequent discharge of dye wastewater have resulted in severe pollution, necessitating urgent development of innovative treatment technologies. This article presents the design of a novel catalyst comprising brucite loaded with nitrogen-deficient carbon nitride nanosheets (FBCN) to activate PMS for the degradation of MB wastewater. The effects of brucite-to-urea ratio, catalyst dosage, PMS concentration, pH value, reaction temperature, natural organic matter and anions, and reusability on MB degradation were investigated. Under optimal conditions, the 12.5%FBCN/PMS system achieved complete degradation (100%) of 10 mg/L MB within 5 min, a significant improvement compared to the FB-600/PMS and g-C3N4/PMS systems. The enhanced catalytic activity can be attributed to the interaction between hydroxyl groups on the surface of brucite and amine groups derived from urea, which accelerates the formation of double nitrogen defects (N vacancies and cyano groups) in g-C3N4 thereby greatly enhancing PMS activation efficiency. In addition, the excellent activation performance of 12.5%FBCN originated from its unique combination to enhance the electron transfer performance between brucite and g-C3N4. The system also generates singlet oxygen radicals (1O2), hydroxyl radicals (·OH), and sulfate radicals (SO4·-), among which 1O2 is identified as being predominantly responsible for MB degradation. This study offers a new approach for designing efficient activators for PMS in environmental remediation.