Abstract: The Fe3O4@MnFe-LDH magnetic catalyst was prepared by a two-step method to enhance the efficiency of peroxymonosulfate (PMS) oxidative degradation of Congo red. Its morphological characteristics and structural composition were analyzed, and the effects of initial pH value, catalyst dosage, PMS dosage, initial concentration of Congo red, and reaction temperature on the degradation performance of Congo red were explored. The stability and reusability of Fe3O4@MnFe-LDH were evaluated through cycling experiments and material characterization before and after reaction. In addition, radical quenching experiments, liquid chromatography-mass spectrometry (LC-MS), and the toxicity estimation software tool (T.E.S.T.) were employed to elucidate the reaction mechanism, degradation pathways, and changes in pollutant toxicity. The research results show that Fe3O4@MnFe-LDH possesses a high specific surface area and mesoporous structure, and its surface contains redox-active sites of Mn (Ⅱ)/Mn (Ⅲ) and Fe (Ⅱ)/Fe (Ⅲ), as well as functional groups such as hydroxyl and carbonate groups. Radical quenching experiment confirms that the synergistic effect of the Fe-Mn bimetallic system, involving the valence cycling of Mn(Ⅱ)/Mn(Ⅲ) and Fe(Ⅱ)/Fe(Ⅲ), activates PMS through electron transfer and promotes the generation of sulfate radicals (SO4·-), superoxide radicals (O2·-), singlet oxygen (1O2), and hydroxyl radicals (·OH). Congo red is oxidized by free radicals and gradually degraded through processes such as azo bond breakage and sulfonic acid group removal, but it is not completely mineralized. Instead, it generates seven different intermediate products, most of which have lower developmental toxicity than the original pollutant.

Key words: environment engineering; persulfate oxidation technology; magnetic materials; activator; layered double hydroxide

摘要： 通过两步法制备Fe3O4@MnFe-LDH磁性催化剂，以提升过一硫酸盐（PMS）氧化降解刚果红的效率，并对其形貌特征和结构组成进行分析，探究初始pH值、催化剂投加量、PMS投加量、刚果红初始浓度、反应温度对刚果红降解效果的影响，通过循环实验及反应前后的材料表征，评估Fe3O4@MnFe-LDH的稳定性与重复利用性；并借助自由基猝灭试验、液相色谱-质谱联用（LC-MS）、毒性评估软件（T.E.S.T.）研究其反应机制、降解路径及污染物毒性变化。研究结果表明：Fe3O4@MnFe-LDH具有高比表面积和介孔结构，材料表面存在Mn(Ⅱ)/Mn(Ⅲ)与Fe(Ⅱ)/Fe(Ⅲ)的氧化还原活性位点及羟基、碳酸根等官能团；自由基猝灭实验证实，铁锰双金属协同效应Mn(Ⅱ)/Mn(Ⅲ)与Fe(Ⅱ)/Fe(Ⅲ)价态循环，通过电子转移活化PMS可促进硫酸根自由基（SO4·-）、超氧自由基（O2·-）、单线态氧（1O2）和羟基自由基（·OH）的生成；刚果红被自由基氧化，经偶氮键断裂、磺酸基脱除等过程逐步降解，但并未完全矿化，而是生成7种不同中间产物，中间产物的发育毒性多低于原始污染物。

关键词: 环境工程；过硫酸盐氧化技术；磁性材料；活化剂；层状双氢氧化物