Fe(III) Alleviates pH Dependence of Iron-based Bimetallic/PMS System for Organic Pollutant Oxidation

• Published in: Applied catalysis. B, Environmental Environmental, 2025-06, Vol.366, p.125002, Article 125002
• Main Authors: Yuan, Chaowei, Li, Gefei, Ran, Maoxi, Yang, Wei, Shu, Pingyin, Long, Xizi, Li, Wei
• Format: Article
• Language: English
• Subjects: Anti-interference; Bimetallic spinel; Fe(III); Iron sludge; Peroxymonosulfate activation
• ISSN: 0926-3373
• DOI: 10.1016/j.apcatb.2024.125002

This work delves into the mechanism enabling pH interference resistance in iron-based bimetallic oxides within the peroxymonosulfate (PMS) system. We employed MnFe₂O₄ spinel oxides as a catalyst for an in-depth comparison with monometallic analogs. We discovered that Fe(III) sites within the bimetallic oxide serve as sacrificial sites for hydroxyl ions as pH rises, stabilizing the cycling of active Mn sites. Elevated pH promotes the formation of surface hydroxyl groups, which enhance PMS and phenol adsorption via hydrogen bonding, thereby facilitating PMS activation by adjacent Mn sites and accelerating phenol degradation on the catalyst's surface. The cooperative effects of Fe(III) sacrifice and enhanced hydrogen bonding contribute significantly to the expanded pH tolerance of the iron-based bimetallic system, achieving nearly a 4.9-fold increase in kinetic efficiency at pH 6.2 relative to pH 3.2. This study deepens our understanding of sustainable Fenton-like systems and highlights their promising role in the degradation of pollutants. [Display omitted] •Removal performance of the MnFe2O4/PMS across pH levels was investigated.•Active species variation in the MnFe2O4/PMS system was identified.•Mechanism of broad pH applicability in the MnFe2O4/PMS was uncovered.•Mechanism was widely validated in a variety of iron-based bimetallic oxides.•Practical application potential of the MnFe2O4/PMS was investigated in detail.