Enhanced PMS activation via dual redox cycles in Fe2O3/VO2 bimetallic catalyst for efficient degradation of SCP

In this study, limitation of Fe₂O₃ activity in peroxymonosulfate (PMS) activation processes caused by the Fe²⁺/ Fe³⁺ redox cycle could be addressed by successfully preparing the bimetallic catalyst Fe₂O₃/VO₂ with introducing V. Fe₂O₃/VO₂ were synthesized using a solvothermal method and Fe/V molar ratios (X = 1, 2, 3) were regulated, in which optimal Fe/V ratio of 2:1 demonstrated superior PMS activation to efficiently degrade sulfachloropyridazine (SCP). The Fe₂O₃/VO₂/PMS system exhibited excellent catalytic performance across a wide pH range (3–9), achieving complete degradation of SCP with 0.25 mM PMS in 10 min. Anions (Cl⁻, NO₃⁻, H₂PO₄⁻, HPO₄²⁻, HCO₃⁻) and humic acid showed varying inhibitory effects on SCP oxidation. The Fe₂O₃/VO₂ catalytic system activates PMS through electron transfer from Fe²⁺/ V⁴⁺, simultaneously initiating both radical (SO₄⁻ and OH) and non-radical (primarily ¹O₂) pathways, whose synergistic effect enables highly efficient pollutant degradation. The synergistic effects of these ROS facilitated efficient antibiotic degradation, with ¹O₂ identified as the primary active species. Using HPLC-MS, 13 intermediate products were identified, and three degradation pathways were proposed. Ecotoxicity assessment indicated that most intermediates were significantly less toxic than SCP, confirming the Fe₂O₃/VO₂/PMS system's potential for wastewater remediation.