Effective degradation of 2,4,4?-trichlorodiphenyl by Fe3C@Fe-800 activated peroxymonosulfate: Superoxide radical and singlet oxygen-dominated advanced oxidation process

Polychlorinated biphenyls (PCBs) degradation by peroxymonosulfate (PMS) activation through center dot OH and SO4 center dot- radical oxidation process was the effective technology in the last decades; however, there were few research focusing on removing PCBs by O2 center dot- and 1O2 induced by PMS activation. In this work, 90.86% of 2,4,4-trichloro-diphenyl (PCB 28) was degraded by 0.3 g/L Fe3C@Fe-800 activated 0.5 mM PMS system under the synergistic action of O2 center dot- and 1O2. The structures of Fe3C@Fe-800 were identified by Scanning electron microscope (SEM), High resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), Raman spectra and Fourier transform infrared (FT-IR) spectra. Electron paramagnetic resonance (EPR) measurements and quenching tests verified that O2 center dot- and 1O2 were the primary reactive species in Fe3C@Fe-800/PMS/PCB 28 ternary reaction system. Density functional theory (DFT), Linear sweep voltam-metry (LSV), and chronoamperometry test revealed that electron-deficient Fe atoms on Fe3C were the main active sites in Fe3C@Fe-800 for PMS activation to generate 1O2. Unlike the reported center dot OH and SO4 center dot- mediated degradation induced by the iron-based catalyst, both O2 center dot- and 1O2 contributed to PCB 28 degradation: nucle-ophilic dichlorination reaction by O2 center dot-and then ring-open oxidation process by 1O2. Fe3C@Fe-800/PMS system had excellent catalytic performance under different reaction conditions and possessed desirable inorganic salt and natural organic matter resistance. This work elucidated the important role of Fe3C in PMS activation to generate O2 center dot-and 1O2 for PCB 28 decontamination by nonradical way and provided a clue to design rationally catalysts in polychlorinated biphenyl pollution remediation.

Automated summary

In this study, the synergistic action of O2- and 1O2 produced by PMS activation was successfully utilized to degrade PCB 28. The important role of Fe3C in generating O2- and 1O2 for PCB 28 decontamination was clarified, providing insights for the design of catalysts in polychlorinated biphenyl pollution remediation.