Persulfate activation by novel iron–carbon composites for organic contaminant removal: Performance, mechanism, and DFT calculations

Abstract

• Novel Fe–C was prepared that can efficiently degrade organic pollutants. • Effects of important parameters on MO degradation were investigated. • Primary reactive oxygen species examined by quenching experiments and ESR. • Possible pathways proposed based on LC-MS and DFT calculation calculations. Persulfate (PDS) activation is an effective approach for removing organic pollutants from industrial wastewater, but a more cost-effective catalyst is required. In this study, novel iron–carbon (Fe–C) granules were successfully prepared by a facile calcination method and were applied to PDS activation. Radical quenching experiments, electron spin resonance spectroscopy, and electrochemical analyses were performed to investigate the removal efficiency of methyl orange (MO) by the Fe–C/PDS process and the effects of influencing factors such as the Fe–C dosage, PDS concentration, initial pH, and MO concentration. Fe–C was observed to have a pore structure and abundant functional groups that are beneficial for PDS activation and pollutant removal. The MO removal mechanisms of the Fe–C/PDS process included adsorption, degradation, and co-precipitation, among which the degradation process consisted of radical and non-radical pathways involving the formation of SO 4 −· , · OH, O 2 −· , and 1 O 2 as well as electron transfer. Calculations based on density functional theory were used to propose potential degradation pathways of MO. The Fe–C/PDS process exhibited high adaptability to inorganic anions and natural organic matter in aquatic environments and high removal efficiencies of various organic pollutants.