Fe@C carbonized resin for peroxymonosulfate activation and bisphenol S degradation

Aiming at realizing heavy metal recycling and resource utilization, a carbon-based iron catalyst (Fe@C) was synthesized through a resin carbonization method, and adopted for peroxymonosulfate (PMS) activation to remove bisphenol S (BPS), an emerging aquatic contaminant. This study demonstrated that Fe@C exhibited excellent catalytic potential for BPS degradation with a relatively low activation energy (E_a = 29.90 kJ/mol). Kinetic factors affecting the activation performance were thoroughly investigated. The obtained results indicated that Fe@C composite exhibited the superior uniformity with carbon as the framework and granular iron oxide as the coverage. pH increase could cause the inhibitive effect on BPS degradation, while the increasing catalyst loading (0.05-0.5 g/L) was conducive for the catalytic performance of Fe@C, with an optimal PMS concentration at 1.0 mM. A negative influence on BPS degradation was obtained in the presence of SO₄^2-, HCO₃^- and lower concentration of Cl^- (0-20 mM), compared to the promotion at higher concentration of Cl^- (>50 mM). Based on the electron spin resonance (ESR) monitoring and radical scavenging results, it is demonstrated that singlet oxygen, a non-radical species, emerged together with ·SO₄^- and ·OH for BPS degradation. A three-channel catalytic mechanism was verified through typical characterizations. Furthermore, the degradation pathway of BPS was proposed based on the identified intermediates. This novel carbon-based activator for PMS showed notable potential for the waste resin recycling and water decontamination. A novel Fe-based activator carbonized from a saturated resin exhibits excellent performance for Bisphenol S degradation with activated peroxymonosulfate.