Selective degradation of organic pollutants by highly dispersed Fe, Ni anchored on nitrogen carbon activating persulfate system: Electron transfer promotion, the impact of pollutant redox and adsorption properties

Abstract

The advanced oxidation processes using persulfate (PS-AOPs) as oxidant is an effective way to remove refractory organic pollutants from environment. Designing activators with higher activation efficiency and stability plays an important role in degradation of organic pollutants via PS-AOPs. Furthermore, redox and adsorption properties of pollutants also affect the selective degradation efficiency. In this study, we synthesized FeNi@CN derived from ZIF-8 in which highly dispersed Fe and Ni were anchored on nitrogen (N) doped carbon (C). The activator exhibited high activation potential and stability for paracetamol (PCT) degradation by activated peroxymonosulfate (PMS). The FeNi@CN/PMS system degraded PCT through electron transfer pathway, and the coordination of Fe-N and Ni-N improved the efficiency of catalyst mediated electron transfer. The abundant pyridinic N provided a large number of sites for PMS complexation. The bimetallic synergistic effect and N doping endowed the excellent comprehensive performance of FeNi@CN. The significant impact of pollutant redox and adsorption properties on degradation efficiency were also studied. It was observed that high half-wave potential (E1/2) and excessive adsorption were not conducive to electron transfer. Multi-parameter linear fitting was performed on the degradation rates of different pollutants using half-wave potential and pseudo first order adsorption rate constants, which showed the good correlation among them. This work not only provided insights into the mechanism and the influence of activator structure on electron transfer in PMS activation, but also proposed a new model to describe the effects of redox and adsorption properties on selective degradation of various category pollutants.