Preparation Of Magnetic Ferrite Based Nanocomposite Materials And Their Adsorption And Photocatalytic Properties

Water pollution is a major problem for the water resources in our country, it not onlyaggravates the situation of shortage of water resources, but also tremendously destroys theenvironment. Among water treatment technologies, photocatalytic oxidation technologyutilizes nano semiconductor materials as catalysts, which has become a new technologythat attracts extensive concerns in recent years. Semiconductor nano powder materialshave been widely researched in priority and have exhibited a variety of excellentperformance in photocatalysis and adsorption fields. They have showed potentialapplication prospects in the treatment of refractory organic pollutant in wasted water. Atthe same time, when conventional single-semiconductor nano powder materials areutilized in the photocatalysis field to treat organic pollutant in waste water, many problemsstill exist,such as low quantum efficiency, low utilization rate of visible light, and difficultto be recovered., These problems would hinder the direct applications of these materials inthe treatment of water. Therefore, the preparation of magnetic ferrite compositesemiconductor photocatalysts with high photocatalytic activity and good recycle abilityhave important theoretical and practical value for the large scale applications ofsemiconductor photocatalysts.In this thesis, the main study is that the nano ferrite materials with strong magneticproperty and stability were synthesized using solvothermal method, and then a series ofFerrite/Inorganic Semiconductor, Ferrite/Organic Semiconductor and Ferrite/OrganicSemiconductor/Noble Metal nanocomposite materials were prepared with the externalloading method in low temperature liquid phase conditions based on the nano ferritematerials. The photocatalytic activity, adsorption performance and stability of thesenanocomposite materials were investigated by treating the simulated waste watercontaining organic azo dyes. The main research findings could be summarized asfollowed:(1) Firstly, the Fe3O4nano crystalline microspheres were prepared with solvothermalmethod, and then the Fe3O4/BaTiO3nanocomposite material was synthesized using thesol-gel and calcination methods based on the Fe3O4nano crystalline microspheres. Theproducts were characterized by XRD, SEM and VSM techniques. The influence was mainly investigated of the heating and cooling rates, the calcination temperatures of thecrystal structures, and the microstructures of the Fe3O4/BaTiO3nanocomposite materialThe photocatalytic activity in degradation of azo dyes in the simulated waste water underUV light irradiation was also researched. The results of the study showed that: A relativehigh dispersive cube shaped Fe3O4/BaTiO3core shell nanocomposite material wasobtained after being calcined at523K for0.5h under N2protection, rapid heating, andcooling rates conditions. The nanocomposite material had strong saturation magnetizationand good magnetic response property, hence they had good recyclable performance. Thephotocatalytic experiments revealed that the nanocomposite material could decompose azodyes, but their quantum efficiency and photocatalytic activity were not as high asexpected.(2) A series of Fe3O4/PPy,Fe3O4/PPy/Ag and Fe3O4/Ag/PPy nanocompositematerials were prepared by loading noble metal Ag and conductive polymer polypyrrole,which has both good adsorption property and high photocatalytic activity on the surface ofFe3O4nano crystalline microspheres, using free radical polymerization and chemicalreduction methods. The characterization of these materials was also carried out. Theadsorption property of the Fe3O4/PPy nanocomposite material on azo dyes in thesimulated wasted water was studied. The photocatalytic activity of Fe3O4/PPy,Fe3O4/PPy/Ag and Fe3O4/Ag/PPy nanocomposite materials in degradation of azo dyesunder UV and visible light irradiation were also investigated. The relation between theload position, the amount of Ag, and the photocatalytic performance were mainlyresearched. The results of the study showed that: The adsorption property of theFe3O4/PPy on azo dyes was good, and it was mainly affected by initial pH values,adsorption time, initial azo dyes concentration, and adsorption temperatures. Theadsorption process of azo dyes onto the Fe3O4/PPy was consistent with the Langmuirisothermal adsorption model and the pseudo two order kinetics model. This material hadstrong saturation magnetization, it could be recovered by using a magnetic field, and itcould be regenerated easily. However, the chemical property of Fe3O4are not stable, itcould be oxidized and lose magnetism. As a result, the recovery performance ofFe3O4/PPy were not stable. The load position and the amount of Ag would affect thephotocatalytic performance of Fe3O4/PPy/Ag and Fe3O4/Ag/PPy nanocompositematerials. The Fe3O4/Ag(more)/PPy nanocomposite material with more Ag showed the best photocatalytic performance both under UV and visible light irradiation. Thephotocatalytic activity of Fe3O4/Ag(more)/PPy was higher than that of Fe3O4/BaTiO3under UV light irradiation, and it increased significantly.(3) In order to overcome the shortcomings of Fe3O4, which is easy to be oxidized andunstable magnetism, a series of Fe2O3/PPy, Fe2O3/PPy/Ag and Fe2O3/Ag/PPy wereprepared with the same methods after replacing Fe3O4nano crystalline microspheres withγ-Fe2O3nanoparticles. The adsorption property of the Fe2O3/PPy nanocomposite materialon azo dyes in the simulated wasted water was studied. The photocatalytic activity ofFe2O3/PPy, Fe2O3/PPy/Ag and Fe2O3/Ag/PPy nanocomposite materials in degradation ofazo dyes under UV and visible light irradiation was also investigated. The results of thestudy showed that: The adsorption process of Fe2O3/PPy was similar to that of Fe3O4/PPy.The adsorption performance of Fe2O3/PPy was better, which could be attributed to largerspecific surface area. This material had good magnetic response property, and it could berecovered by using a magnetic field. Besides, it could be regenerated easily by washingwith alkaline solution and can be repetitively used for many times. The Fe2O3/PPy hadstable chemical property and magnetism. It had good magnetic recovery performance afterrecycling for many times. In the photocatalytic experiments, the Fe2O3/Ag(more)/PPynanocomposite material with more Ag showed the best photocatalytic performance bothunder UV and visible light irradiation compared to the Fe3O4/BaTiO3ortheFe3O4/Ag(more)/PPy.