Synergistically enhanced activation of peroxymonosulfate by Fe3O4@ZSM-5 catalysts for ciprofloxacin degradation: Performance, kinetics and mechanism insight

Abstract

Exploring an environmentally friendly and highly activation catalysts in the advanced oxidation processes (AOPs) basing on sulfate radicals (SO4−•) has shown great importance for the remediation of refractory contaminants. Herein, Fe3O4-wrapped ZSM-5 (Fe3O4@ZSM-5) was constructed as heterogeneous catalyst to remove ciprofloxacin (CIP) via peroxymonosulfate (PMS) activation, in which performance, kinetics and mechanism insight were investigated in depth. The removal efficiency of CIP reached 90 % by Fe3O4@ZSM-5 catalysts within 100 min reaction when the initial pH was 3.0. During the reaction, SO4−• and HO• were proved to be coexisted in reaction system and SO4−• played a critical role in CIP degradation according to the radical quenching experiments and electron paramagnetic resonance (EPR) measurements. Based on the catalyst characterization and Langmuir-Hinshelwood adsorption kinetics analysis, the synthesis of Fe3O4 nanoparticles (NPs) and ZSM-5 accelerated the dispersion process and enhanced adsorption ability of Fe3O4 NPs, which further promoted the local concentration of CIP and PMS on the surface. In addition, the cycling experiments and metal leaching tests demonstrated that Fe3O4@ZSM-5 catalysts were stable and could be conveniently reused by magnetic separation. In addition, the impacts of coexisting irons (Cl−, SO42−, NO3−, HCO3−) confirmed that Fe3O4@ZSM-5 was still effective in real water. This study demonstrated the promising prospect of Fe3O4@ZSM-5/PMS system in the application of degradation refractory organic pollutants.