Construction of CoFe2O4/g-C3N4 heterojunction for under visible light PMS activation: ROS contribution order and mechanism

The integration of photocatalytic process with peroxymonosulfate (PMS) activation constitutes a promising strategy for eliminating organic pollutants in aqueous solutions. Despite notable advances in CoFe 2 O 4 /g-C 3 N 4 composites, studies on their application in visible-light-responsive PMS-activated tetracycline (TC) degradation remain insufficient, particularly in the systematic elucidation of the quantitative order of ROS contributions and associated mechanisms. To address this knowledge gap, a recyclable CoFe 2 O 4 /g-C 3 N 4 heterojunction photocatalyst was prepared via the sol–gel method. The composites demonstrated outstanding photocatalytic performance with 97.8% TC degradation in 60 min under visible-light irradiation. The kinetic rate constant of 0.056 min −1 , which was 3.7 and 3.2 times that of pure g-C 3 N 4 (0.015 min −1 ) and CoFe 2 O 4 (0.017 min −1 ). Moreover, the developed catalyst exhibited excellent stability along with tolerance to common anions and compatibility with various organic matrices. By coupling radical quenching experiments with ESR spectroscopy, a definitive degradation contribution order for the reactive species in this system was firstly established as: 1 O 2 > SO 4 · - > O 2 · - > h + > · OH. A plausible mechanism for TC degradation was thus put forward. It provides a viable approach for developing high-performance and durable g-C 3 N 4 -derived photocatalytic system, which can be effectively utilized in environmental remediation process.