Understanding Iron-Cobalt Synergies in Zsm-5 : Enhanced Peroxymonosulfate Activation and Organic Pollutant Degradation

Iron and cobalt-based heterogeneous catalysts are widely applied for activating peroxymonosulfate (PMS) to degrade organic pollutants. However, little study had unveiled a clear synergistic mechanism of iron and cobalt in ZSM-5. In this paper, the synergistic mechanism of enhanced PMS activation was demonstrated by constructing iron and cobalt bimetal modified ZSM-5 zeolites catalysts (FeCo-ZSM-5). The tetracycline hydrochloride (TCH) degradation experiments showed that the catalytic activity of FeCo-ZSM-5-2:3 was much higher than Fe-ZSM-5 and Co-ZSM-5. In addition, this paper systematically investigated the influence on catalyst dosage, PMS concentration, reaction temperature, initial pH, and coexisting ions on TCH removal. DFT calculations revealed that the Fe-Co bimetallic doping had synergistic effects on promoting the distribution range of the positive potential, which benefited the adsorption of PMS on the catalysts surface. Electron paramagnetic resonance (EPR) spectra and quenching experiments showed that sulfate radicals, singlet oxygen, and hydroxyl radicals were involved in the degradation of TCH. Finally, liquid chromatography-mass spectrometry (LC-MS) was conducted to propose possible degradation pathways. This work provides certain guiding significance on understanding the synergistic effect of heterogeneous catalysts for tetracycline wastewater treatment