The efficient degradation of paracetamol using covalent triazine framework-derived Fe-N-C activated peroxymonosulfate via a non-radical pathway: Analysis of high-valent iron oxide, singlet oxygen and electron transfer

Abstract

The abundant and environmentally friendly metal iron (Fe) is an excellent candidate to activate peroxymonosulfate (PMS) for the oxidative decomposition of organic pollutants. However, Fe-based activators have disadvantages of high efficiency only in a narrow pH range and easily generated Fe-sludge. Therefore, developing wide pH range efficient and stable Fe-based PS activators is needed. In this study, iron–nitrogen-carbon (Fe-N-C) activators were prepared using covalent organic frameworks containing homogeneous micropores and high porosity as a precursor. The Fe-Nx-rich activator showed an outstanding activity and a high stability in the heterogeneously activated PMS system. It found that the 10 mg/L paracetamol (PCT) could be degraded completely within 5 min when adding 30 mg/L activator and 3 mM PMS. Furthermore, the system shows good performance in an extensive buffer pH range (2.6–10.67). The quenching experiments and intermediate product tests supported that the high-valent iron-oxo species is the major reactive oxygen species (ROS) in this system, and the designed experiments confirmed that Fe-N as the active site that in charge of activating PMS. This work provides insights for improving the activation efficiency and expanding the pH working range of iron-based catalysts in the field of advanced persulfate oxidation.