Experimental Study On The Treatment Of Organic Pollutants In Water By Activating Persulfate With Magnetic Manganese Ferrite Composite

Sulfate radical(SO₄^·-)-based advanced oxidation technology has been widely used in environmental pollution control.The technology mainly generates sulfate radicals(SO₄^·-)hydroxyl radicals（·OH）and strong oxidizing non-radicals and other active substances by activating persulfate（PDS）and realize the efficient degradation of pollutants.However catalysts for activating persulfate generally have problems such as high cost low performance or difficulty in recycling.Therefore the development of low-cost high-efficiency and environmentally friendly catalysts is one of the important topics in the research field of sulfate radical(SO₄^·-)-based advanced oxidation technology.In this study using magnetic manganese ferrite as the basic material using magnetic manganese ferrite as the basic material two catalysts with excellent activation properties for persulfate were synthesized through low-temperature co-precipitation and hydrothermal methods.The main research contents and results are as follows:（1）MnFe₂O₄ is used as the matrix with the different Fe/Zr molar ratio the magnetic ZrO₂/MnFe₂O₄ was synthesized via hydrothermal co-precipitation method.Taking tetracycline（TC）as the target pollutant the removal efficiency of MnFe₂O₄ on TC before and after loading was studied and compared.Compared to pure MnFe₂O₄the ZrO₂/MnFe₂O₄ exhibited excellent catalytic performance.Moreover the TC removal efficiency reached 85.2%under the optimum reaction condition（Fe/Zr molar ratio initial pH PDS concentration and ZrO₂/MnFe₂O₄ dosage were 10 7.1 6.0 m M and 0.2 g/L respectively）.Nevertheless the TC removal efficiency was different extents inhibited by inorganic anions（H₂PO₄^->HCO₃^->NO₃^->Cl^-）and organic substances（EDTA>HA）.In the cycling study the magnetic ZrO₂/MnFe₂O₄ maintains satisfactory stability and high catalytic activity.Additionally the potential mechanism of ZrO₂/MnFe₂O₄ composite activating PDS was proposed by quenching tests EPR studies as well as XPS analysis results.Based on the degradation products determined by UPLC-MS the possible four degradation pathways of TC removal were proposed in the ZrO₂/MnFe₂O₄/PDS system.All these results indicate that the prepared magnetic ZrO₂/MnFe₂O₄ ensures efficient removal of different organic pollutants exhibits prominent magnetic separation and reusability which will be contributed to its practical application.（2）A magnetic graphene-like porous biochar MnFe₂O₄/KFS800 composite material was synthesized by hydrothermal method and its catalytic activity was tested by catalytic PDS to remove the rhodamine B（RhB）form water.The MnFe₂O₄/KFS800catalyst was characterized by VSM SEM XRD FTIR XPS and BET.The results show that the superparamagnetic MnFe₂O₄/KFS800 catalyst has been successfully prepared.It has good crystallinity composed of spherical and layered materials containing many hydroxyls and carboxyl functional groups and the specific surface area and total pore volume are as high as 121 m²/g and 0.263 m³/g.When the initial concentration of RhB is 10 mg/L the dosage of MnFe₂O₄/KFS800 is 0.1 g/L the pH is6.7 the reaction time is 60 min the reaction temperature is 30℃the speed is 200r/min and the water sample volume is 100 m L the removal efficiency of RhB reached88.2%.In addition inorganic anions have different degrees of RhB removal（H₂PO₄^->NO₃^->Cl^->HCO₃^-）in the MnFe₂O₄/KFS800/PDS system.Furthermore the presence of HA has little effect on the removal of RhB by the MnFe₂O₄/KFS800/PDS system which also shows that the system has good resistance to the water body where HA exists.In the cyclic study the magnetic MnFe₂O₄/KFS800 still maintained a 75.2%RhB removal efficiency after 5 times of use.Moreover through quenching test EPR research and XPS analysis results the potential mechanism of MnFe₂O₄/KFS800activation PDS is proposed:the oxidative removal of RhB by the MnFe₂O₄/KFS800/PDS system is completed under the combined action of free radicals(SO₄^·-·OH and O₂^·-)and non-free radicals（¹O₂）.