The Study On The Liquid Preparation And Photocatalytic Capability Of Nano Zinc Based Oxide

ZnO is a direct band gap semiconductor with a band gap width of 3.37 ev.ZnO has a similar band gap and photocatalytic mechanism with traditional TiO₂photocatalyst in the photocatalysis domain.ZnO is considered to be one of the ideal candidate materials for the replacement of titanium dioxide photocatalyst.ZnO has good chemical stability,non-toxic and environmental protection,high quantum efficiency,excellent oxidation ability and low preparation cost.Low preparation cost ZnO has been widely used as a good photocatalyst because of its anisotropic crystal structure and easy to obtain powders with different morphology and excellent photocatalytic properties.In addition,in order to achieve magnetic separation and recovery under external magnetic field and avoid secondary pollution,we introduce zinc ferrite as photocatalyst,ZnFe₂O₄ is also a very good photocatalytic material sensitive to visible light.Its band gap width is about 1.9 ev and makes the material a narrow band gap semiconductor material.Due to its stable photochemical properties,non-toxic components,low preparation price,easy to be excited by visible light and can absorb sunlight under 700nm,it has been used as photocatalysis in the visible light band.For the purpose of improving the photocatalytic activity of zinc ferrite,graphene can be used as a supporting substrate to immobilize zinc ferrite nanoparticles on its surface,thus preventing the agglomeration of zinc ferrite nanoparticles,and increasing the effective contact area with organic pollutant particles.At the same time,it has a high carrier migration efficiency,which can make photoelectrons jump rapidly,avoid compound with holes,and thus improve the agglomeration of zinc ferrite nanoparticles The photocatalytic efficiency is improved.The purpose of this paper is to prepare the high photocatalytic activity,magnetic recovery of nano zinc based oxide photocatalyst.In this paper,ZnO,ZnFe₂O₄,ZnO/ZnFe₂O₄ and ZnFe₂O₄-rGO were prepared by liquid phase method.The photocatalytic activity and magnetic recovery of organic pollutants were investigated.（1）ZnSO₄·7H₂O and Zn（NO₃）₂·6H₂O were used as two kinds of zinc sources,urea,sodium bicarbonate（NaHCO₃）and hydrazine hydrate were used as alkali sources.ZnO crystals were prepared by the low temperature co-precipitation method and hydrothermal method.Their morphology,specific surface area,growth mechanism and photocatalytic performance were characterized.A method of preparing ZnO crystal with high photocatalytic activity was proposed.（2）ZnO/ZnFe₂O₄ is a simple solvothermal method to prepare ZnO/ZnFe₂O₄photocatalyst composite with different molar ratio.The structure,morphology,growth mechanism,photodegradation activity and magnetic recovery performance of ZnO/ZnFe₂O₄ photocatalyst composite were studied.A kind of ZnO/ZnFe₂O₄nanocomposite with the visible light response and magnetic separation and recovery under external magnetic field was studied.（3）ZnFe₂O₄-rGO powder was prepared by solvothermal method with ethanol as solvent,Zn（NO₃）₂·6H₂O and Fe（NO₃）₃·9H₂O as two raw materials,and then the graphene dispersion was added to the ZnFe₂O₄-rGO powder.And these magnetic composite materials are easy to be recycled and can be used as photocatalytic materials to remove organic pollutants in water treatment process.