Study On Photo-fenton Properties Of Magnetically Reclaimed MnFe₂O₄ Composite Photocatalyst

Manganese ferrite（MnFe₂O₄）is a narrow band gap spinel type ferrite,and has excellent physical and chemical properties such as adsorption and soft magnetic properties.It is widely used in the fields of magnetic photocatalysis and advanced oxidation technology.In this paper,MnFe₂O₄ nanoparticles were prepared by hydrothermal method,and combined with graphene（rGO）,tin disulfide（SnS₂）and ceria（CeO₂）to modify the band gap structure of MnFe₂O₄ to improve the photo-Fenton performance of MnFe₂O₄.The properties of the composites were characterized by XRD,SEM,TEM,UV-vis DRS,XPS,VSM,FT-IR,PL,Raman and other characterization methods.The Xenon lamp was used to simulate the sunlight,and the dye methylene blue（MB）was used as the degradation target to evaluate the photo-Fenton performance of the composite photocatalyst.Its main content is:Firstly,MnFe₂O₄ nano-ellipsoid particles with an average particle size of 75 nm were successfully prepared by hydrothermal method.Graphene oxide was prepared by Hummers method.Using the reductive property of hydrothermal method,manganese ferrite/thermal reduction graphene oxide（MnFe₂O₄/rGO）was finally prepared by one-step hydrothermal method.It was found by TEM that the graphene sheets were bonded with manganese ferrite nanoparticles.According to DRS,the band gaps of MnFe₂O₄ and MnFe₂O₄/rGO are estimated to be 2.44 eV and 2.13 eV,respectively.The photocatalyst after the reaction can be recovered by magnetite.Photocatalytic experiments show that the photocatalytic activity of fenfuron-based MnFe₂O₄/rGO composites is significantly enhanced compared to pure MnFe₂O₄.Active free radical detection was carried out by adding different capture agents,and it was found that hydroxyl radicals and electrons were the main active substances.By analyzing the optical Fenton mechanism,it was found that the composite material has two effective ways to degrade to degrade methylene blue.Second,a magnetically separated MnFe₂O₄/SnS₂ composite was successfully synthesized by a simple and economical hydrothermal method.The structure and morphology of the composites were characterized by XRD,SEM and TEM.It can be seen from the light Fenton experiment that the prepared composite material has good photo-Fenton activity and magnetic responsiveness,and has a significant effect on the recovery and reuse of MnFe₂O₄/SnS₂ composite materials.By comparison,it was found that MnFe₂O₄/SnS₂-10%had the best degradation under visible light irradiation.The effects of solution pH and H₂O₂ dosage on the oxidation of photofenton were investigated.Through 5 cycles of experiments,it was found that binary composites have better cycle stability.Therefore,the MnFe₂O₄/SnS₂ composite prepared by simple synthesis process has high magnetic response and excellent photo-Fenton performance,and has broad application prospects in the field of photodegradation.Third,the ternary composite material MnFe₂O₄/CeO₂/SnS₂ was prepared（composite ratio:1:0.2:0.5,1:0.2:1,1:0.2:1.5）.The performance of heterogeneous photo-Fenton degradation of methylene blue in MnFe₂O₄/CeO₂/SnS₂ composites at neutral pH was investigated and compared with photocatalysis.The results show that the degradation effect of photo-Fenton is better than that of photocatalysis,and the degradation efficiency of methylene blue is high,and it is easy to recover under external magnetic field.This allows for efficient reuse of the catalyst without substantial loss of activity in the catalytic cycle,which is a very interesting prospect for a recyclable dye degradation system.