Synthesis Of ZnFe₂O₄ And Their Properties Of Decomposition For Organic Dye Wastewater

With the rapid development of industry,the treatment of industrial waste water has become an important problem to be resolved.Spinel ferrites AFe2O4(A=Co,Zn,Mg etc.)have attached many attentions for their excellent magnetical,chemical properties and their great potential applications.As effective visible light photocatalysts,the bandwidth of spinel ferrites is from 1.9e V to 2.3e V,which can effectively absorb the visible part of the energy.Nevertheless,ferrite oxides also can show excellent adsorption as long as they show large surface area.In this work,ZnFe2O4 nanoparticles,ZnO/ZnFe2O4 and ZnFe2O4 nanospheres were prepared.The structure,morphologies,magnetic and photocatalytic activity of ferrites were studied.1.Microwave treatment is used to improve the photocatalytic activity of ZnFe2O4 nanoparticles.ZnFe2O4 have been primarily synthesized through a sol-gel method and solid state method.Subsequently they are irradiated by microwave treatment for 10 min using NH4 Cl as dispersant.Compared to ZnFe2O4 without microwave treatment(ZFO),M-ZFO exhibits smaller particle size,higher crystallinity,higher surface area and larger saturation magnetization.More importantly,the photocatalytic activity of M-ZFO for Methylene Blue(MB)is increased by 25% compared with ZFO.2.ZnO/ZnFe2O4 magnetic nanoparticles have been synthesized by a rapid microwave combustion method using Na Ac as fuel.With increasing in Na Ac dosage,the reactants generate amount of gases during the combustion process,which can prevent the particles from growing larger.Therefore,the size of the ZnO/ZnFe2O4 nanoparticles decrease,SBET increases,and removal capacity is higher with the mass of Na Ac increasing.Moreover,ZnO/ZnFe2O4 exhibits a high saturation magnetization,and the adsorption equilibrium data fit Langmuir isotherm equation well with a maximum MB adsorption capacity of 37.27 mg/g.3.ZnFe2O4 nanospheres have been synthesized by solvothermal method using different assisting agents(sodium acetate,ammonium acetate and urea)as assisting agents.Sodium acetate is selected as the best auxiliary agent due to the excellent photocatalytic effect of ZnFe2O4,and the synthesized Zn1-x Fe2O4 with different ratio of Znand Fe.Morphology,structure and magnetic properties of the nanospheres are investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD),vibrating sample magnetometer(VSM).Hydrothermal method is also used in the synthesis of ZnFe2O4 nanospheres.The optimal ZnFe2O4 conditions are found by changing reaction time,amount of urea and dosage of PAM(polyacrylamide).Moreover,the adsorption properties of ZnFe2O4 nanospheres are researched and find the optimal p H and maximum adsorption capacity of methylene blue and basic fuchsine.