MnFe2O4活化过一硫酸盐降解废水中LAS

采用共沉淀法制备了铁锰双金属复合催化剂（MnFe₂O₄），用于活化过一硫酸盐（PMS）产生强氧化性的硫酸根自由基（SO₄^-·）氧化降解水中阴离子表面活性剂（LAS）.采用傅立叶变换红外光谱仪（FTIR）、X射线粉末衍射仪（XRD）、扫描电子显微镜（SEM）对催化剂进行表征，表明成功合成了具有尖晶石结构的MnFe₂O₄催化剂.考察了催化剂投加量、PMS投加量以及初始pH值等各种因素条件对LAS的降解效率以及反应动力学的影响.实验结果表明，MnFe₂O₄活化PMS降解LAS的过程符合准一级动力学（R²>0.9）.在LAS初始浓度为80mg/L，催化剂投加量为2.0g/L，PMS的浓度为2.5mmol/L，初始pH值为7.0，反应时间为30min的情况下，LAS降解效率达到94.1%，此时LAS的降解速率常数达到0.192min^-1.通过自由基猝灭实验证明了MnFe₂O₄/PMS体系中起主要氧化降解作用的活性自由基为SO₄^-·.通过反应前后催化剂的X射线光电子能谱（XPS），证实Fe和Mn之间存在协同作用，提高了MnFe₂O₄对PMS的活化效率.

Degradation of LAS in wastewater by peroxymonosulfate activated by MnFe2O4

The Fe-Mn bimetallic composite catalyst MnFe₂O₄ was prepared by co-precipitation method, applied to active peroxymonosulfate (PMS) to generate strong oxidizing sulfate radicals (SO₄⁻·) for oxidative degradation of anionic surfactants (LAS) in water. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffractometry (XRD) and scanning electron microscopy (SEM). It was indicated that the catalyst with MnFe₂O₄ spinel structure was successfully synthesized. Effects of various factors such as catalyst dosage, PMS dosage and initial pH on the degradation efficiency and reaction kinetics of LAS were investigated. The experimental results showed that the MnFe₂O₄ activates PMS to degrade LAS in accordance with quasi-first-order kinetics (R²>0.9). The LAS degradation efficiency can reached 94.1% within 60 min when the initial concentration of LAS was 80mg/L, the catalyst dosage was 2.0g/L, the concentration of PMS was 2.5mmol/L, and the initial pH was 7.0. The degradation rate constant reached 0.192min^-1. The active species that plays a major role in oxidative degradation in MnFe₂O₄/PMS system was identified as SO₄⁻· by radical quenching experiment. By the X-ray photoelectron spectroscopy (XPS) analysis of the catalyst before and after the reaction, the synergistic effect between Fe and Mn was confirmed which in order to improve the activation efficiency of PMS by MnFe₂O₄.