Synthesis,Characterization And Properties Of Spinel Type MFe₂O₄?M= Mn,Cu,Mg?--based Nanomaterials

One of the most pervasive problems affecting people throughout the world is inadequate access to clean water and sanitation.Problems with water are expected to grow worse in the coming decades,with water scarcity occurring globally,even in regions currently considered water-rich.Addressing these problems calls out for a tremendous amount of research to be conducted to identify robust new methods of purifying water at lower cost and with less energy.The development of highly magnetic recyclable adsorbents and photocatalysts is an important direction for material research.The ferrite is widely used in various fields because of its ferromagnetism,good physical properties and chemical properties.In this work,magnetic recoverable ferrites with high adsorption capacity was synthesized by simple and rapid salt-assisted solution combustion method.The photocatalytic activity of ferrites was enhanced by compositing with conductive polymer polyaniline?PANI?or bismuth oxychloride BiOX?X = Cl,Br?to form a heterojuntion.1.Recyclable MFe₂O₄?M = Cu,Mg?nanoparticles were prepared by a facile salt assisted solution combustion method.The obtained samples were characterized by X-ray diffraction?XRD?and scanning electron microscopy?SEM?methods.The results show that fuel type,fuel-to-nitrate ratio?F/N?,KCl-to-metal ions ratio?KCl/M?had significant impacts on the crystal phase composition,crystal structure and morphology of the products.The adsorption performance of the samples was investigated by adsorption removal of Congo red.The results show that product prepared by salt assisted solution combustion method has a good adsorption capacity for Cango red and the Langmuir model fits the experiment data better than the Freundlich model.Furthermore,the initial CR concentrations,adsorption temperatures and contact times play a dramatic role in determining the adsorption capacity.2.The magnetically recyclable MnFe₂O₄/Polyaniline?PANI?composite was successfully synthesized by a combination of a saltassisted solution combustion method and an in situ oxidative polymerization method.XRD,SEM and UV-vis diffuse reflectance spectroscopy were employed to characterize the physical and chemical properties of the samples.The photodegradation experiment showed that the photocatalytic activity and stability of MnFe₂O₄/PANI have a greater effect on the degradation of rhodamine B?RhB?than that of pure PANI and MnFe₂O₄ nanoparticles under visible light irradiation,suggesting the existence of a synergic effect between PANI and MnFe₂O₄.The excited state electrons in the lowest unoccupied molecular orbital?LUMO?of PANI can readily migrate into conduction band?CB?of MnFe₂O₄,while the holes in the valence band?VB?of MnFe₂O₄ migrate to the ?-orbital of PANI because of the enjoined electric fields of the two materials,which can further improve the separation of the photogenerated electron-hole pairs.3.In order to adjust light response range and improve the photocatalytic properties of halogen bismuth oxide?BiOX?,BiOX was composited with CuFe₂O₄ nanoparticles by hydrolysis method.As-synthesized samples were characterized by SEM and XRD methods.Under the visible light irradiation,the photocatalytic performance of these catalysts was investigated by removal of rhodamine B.The results show that the BiOX/CuFe₂O₄ compounds have good crystallinity,and their crystal phase structure was affected by addition of CuFe₂O₄.The composite had a morphology of layer structure with doped CuFe₂O₄ exists between the layers of BiOX?X = Br,Cl?.The light response range of BiOX was broadened and the photocatalytic BiOCl and BiOBr was obviously improved with the addition of CuFe₂O₄,strongly suggesting the formation of heterojunction between BiOX?X=Br,Cl?and CuFe₂O₄.