Hematite (α-Fe₂O₃) has been commonly used as an eco-friendly catalyst for peroxymonosulfate (PMS) to generate free radicals (SO₄^•- and/or •OH). However, the activation efficiency of PMS relies heavily on the conversion of Fe(III) to Fe(II) that is slow and rate-limiting. In this study, oxygen vacancies enriched α-Fe₂O₃ was prepared from thermally treated goethite (α-FeOOH) and employed as a PMS activator. Systematic characterization demonstrated that α-Fe₂O₃ with most abundant oxygen vacancies could be obtained by heating α-FeOOH at 300 °C. The as-prepared α-Fe₂O₃ exhibited excellent catalytic activity in activation of PMS for oxidation of sulfamethoxazole (SMX, k = 0.04 min⁻¹). The SMX degradation rate was found to be positively correlated with the concentration of oxygen vacancies. Quenching experiments, EPR, LC/MS and XPS analysis revealed that singlet oxygen (¹O₂) was the predominant reactive oxygen species. The effects of pH, PMS dosage, catalyst loading, temperature, and anions on SMX degradation were comprehensively investigated. Moreover, the plausible degradation pathways of SMX in the α-Fe₂O₃/PMS system were proposed. This work not only provides a valuable insight into the mechanism of PMS activation by α-Fe₂O₃ but also establishes a new strategy for the design of more efficient and practical iron-based catalyst for PMS activation.

赤铁矿 (α-Fe ₂ O ₃ ) 已普遍用作过硫酸盐 (PMS) 的环保催化剂，以产生自由基（SO ₄ ^•-和/或 •OH）。然而，PMS 的活化效率在很大程度上依赖于缓慢且限速的 Fe(III) 向 Fe(II) 的转化。在这项研究中，由热处理的针铁矿 (α-FeO​​OH) 制备富含氧空位的 α-Fe ₂ O ₃并用作 PMS 活化剂。系统表征表明，通过在 300°C 下加热 α-FeO​​OH 可以获得具有最丰富氧空位的α-Fe ₂ O ₃。制备的α-Fe ₂ O ₃在磺胺甲恶唑氧化的 PMS 活化中表现出优异的催化活性 (SMX, k  = 0.04 min ^-1 )。发现 SMX 降解率与氧空位浓度呈正相关。淬火实验、EPR、LC/MS 和 XPS 分析表明，单线态氧 ( ¹ O ₂ ) 是主要的活性氧物质。综合研究了 pH、PMS 用量、催化剂负载量、温度和阴离子对 SMX 降解的影响。此外，还提出了 SMX 在 α-Fe ₂ O ₃ /PMS 系统中可能的降解途径。这项工作不仅提供了对 α-Fe ₂激活 PMS 机制的宝贵见解。O ₃还为设计更高效、更实用的 PMS 活化铁基催化剂建立了新策略。