Degradation of Tetracycline by Fe-N-Coordinated Porous Carbon Activated PMS: High Dispersibility and Stability

Abstract

Advanced oxidation processes (AOPs) leverage the generation of reactive radicals or non-radical species, which exhibit strong oxidative potential, to effectively degrade recalcitrant pollutants. Herein, Fe₅-NG is synthesized by a one-step calcination method for the degradation of tetracycline (TC). A large nitrogen concentration enhances the activation ability of Fe₅-NG toward PMS, as manifested by 100% degradation of TC within 12 min for TC concentrations below 25 mg L⁻¹ under visible light irradiation. The Fe₅-NG/PMS system degrades TC via the generation of SO₄^•− and ¹O₂, and the presence of Fe(IV) = O species is confirmed. X-ray photoelectron spectroscopy performed on Fe₅-NG before and after the treatment shows that pyridine nitrogen and graphite nitrogen are the primary active nitrogen species responsible for PMS activation, and PMS accelerates the Fe(III)/Fe(II) redox cycle by forming abundant active nitrogen species. The underlying degradation mechanism of the Fe₅-NG/PMS system is investigated, and the non-free radical (¹O₂) pathway is dominant.