| In recent years, with the rapid social and economic development, global environmental pollution becomes more and more serious, and what is more, the industrial wastewater polluting water bodies becomes one of the most important reasons for the global water resources deficiency. Therefore, wastewater treatment has also become a key research issue by nations of researchers. Titanium dioxide (TiO2), as a photocatalyst, is widely used to treat a variety of organic pollutants in industrial wastewater for its features of cheapness, availability, chemical stability, avirulence and relatively high catalytic reactivity and so on. However, because of its broad band-gap (Eg=3.2～4.5 eV), TiO2 can be excited only under irradiation of ultraviolet light, while the sunlight only contains 3%～5% ultraviolet light, so it is ineffectively to utilize. Moreover, it is hard to wholly and inextenso recycle nano-sized TiO2 with the requirements of not only maintaining a high photocatalytic activity but also meeting specific physicochemical properties.In this paper aiming at the problems above, I am going to prepare precursor solution by reacting PVP and Ti(OiPr)4, then to make composite fibers by using the method of electrospinning and sol-gel process, and finally to get TiO2 nano-fibers in uniform diameter distribution by calcining at high temperature. Then, taking TiO2 nano-fibers as a template, I am going to load a layer of Fe3O4 nano-particles on the surface of TiO2 nano-fibers by using the method of ethylene glycol solvent-thermal reaction, in order to make TiO2/Fe3O4 composite nano-fibrous materials with a high visible light photocatalytic activity, which could be recycled by magnetic separation.I characterize the structures and physicochemical properties of the TiO2 nano-fibers and the TiO2/Fe3O4 composite nano-fibers loaded with different amount of Fe3O4 nano-particles by using scanning electron microscope (ESEM), infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Raman spectroscopy (Raman) and UV-visible diffuse reflectance instrument (Uv-Vis/DR), etc. The results show that TiO2 nano-fibers are anatase and in uniform size distribution, that TiO2/Fe3O4 composite nano-fibers are TiO2 nano-fibers loaded with Fe3O4 paritcles of different paritcle diameters raning from several nanometers to dozens of nanometers, which are in uniform paricle distribution, that the loading amount and particle diameters of Fe3O4 paritcles loaded on TiO2 nano-fibers can be regulated by changing the concentration of Fe3O4 preparation solution, and that iron ions ernter TiO2 crystal lattice and Fe3O4 and TiO2 form the heterostructures.And I take the dilute aqueous solutions of Rhodamine B as the degrading model, to investigate the photocatalytic activity and the Rhodamine B degradation rate of the TiO2 nano-fibers and the TiO2/Fe3O4 composite nano-fibers loaded with different amount of Fe3O4 nano-particles. The results show that there is mainly no photocatalytic activity of TiO2 nano-fibers in the visible region, with the final degradation rate of 31.60% and the degradation coefficient of 3.51 in nine hours, that there is a strong catalytic activity of the TiO2/Fe3O4 composite nano-fibers in the visible region, with the final degradation rate of 97.56% and the degradation coefficient of 10.84 in nine hours, and that the photocatalytic activity of TiO2/Fe3O4 composite nano-fibers changes with the loading amount of Fe3O4 paricles. Since Fe3O4 paricles with particle diameters ranging from several nanometers to dozens of nanometers having superparamagnetism, it is helpful to use external magnetic field to solve the problems of separating and recycling TiO2/Fe3O4 composite nano-fibers in solid-liquid phase reaction systems.
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