Fe/N-codoped carbocatalysts loaded on carbon cloth (CC) for activating peroxymonosulfate (PMS) to degrade methyl orange dyes

Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are encouraging methods for wastewater treatments, but the recycling of used PMS activators in powder form from the wastewater treatment system is still problematic. In this paper, we designed a novel and highly effective carbocatalyst for PMS activation, which was achieved by pyrolyzing the hybrids of metal–organic framework MIL-101(Fe) and dicyandiamide immobilized on the surface of carbon cloth (CC), and a facile route for the preparation of fibrous catalysts was developed. The resultant CC loaded with Fe/N-codoped carbocatalyst exhibited desirable reusability and good stability for the degradation of organic dyes. The mechanism of the novel Fe/N-codoped carbocatalyst for PMS activation including the specific roles of N species and Fe-N binding was investigated. It was demonstrated in electrochemical impedance spectroscopy (EIS) results that the CC facilitated the electron transport of the carbocatalyst in AOPs. It was shown in the radical quenching and electron paramagnetic resonance (EPR) experiments that both the radical and non-radical pathways were accountable for the degradation of contaminants, and the non-radical path was principal. It was also evident in the X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) results that pyridinic N and graphitic N were the main active species for PMS activation.