Novel hemin-derived Fe/N–C magnetic catalyst for enhanced peroxymonosulfate activation and diclofenac degradation

Abstract

In this study, Fe involved N-doped carbon catalysts labelled as PA@Hem_x (x = pyrolysis temperature) was synthesized through a one-step pyrolysis of hemin (Hem) and polyacrylate (PA). The reported method enables high dispersion and exposure of both Fe and N active sites on PA derived carbon. The PA@Hem_x samples were then used for peroxymonosulfate (PMS) activated diclofenac (DCF) degradation. Results from the characterization studies verified the successful incorporation of hemin in the composite. Approximately 99.2 % DCF degradation at pH = 6.01 was achieved in 60 min using 0.1 g L⁻¹ PA@Hem₇₀₀ and 1.0 mM PMS. The pseudo-second-order kinetic model and Langmuir model were used to described the uptake and equilibrium process in DCF/PA@Hem₇₀₀ system. Scavenging and electron-spin-resonance studies showed a non-radical singlet oxygen species (¹O₂) dominates over ^•OH and SO₄^•− radicals in the system. The role of electron transfer was also verified via chronoamperometry and electrochemical-impedance spectroscopy techniques. Furthermore, the PA@Hem₇₀₀/PMS remained highly active towards DCF degradation even in the presence of common anions, humic acid, and various water matrices. The developed catalyst exhibited a TOC removal of 65.8 %. The study also established the potential of PA@Hem₇₀₀/PMS to degrade other organic pollutants (e.g., tetracycline (TC), simazine (SIM), and sulfamethoxazole (SMX)). The results from this study are expected to advance research on synthesizing other novel polymer-based Fe/N–C catalysts for degrading organic pollutants.