| Ti O2 photocatalyst has been the research hotspots in the field of photocatalysis and is expected to become one of the most promising green-type catalyst, since it poses many advantages, such as low-cost preparation, non-toxic, anti-light corrosion and chemical stability, etc. However, the application of Ti O2 catalyst was inhibited because of two disadvantages as follow: 1) The catalyst is difficult to be recycled and reused in the next procedure due to its small particle size; 2) The utilization efficiency of sunlight is low because of its wide band gap, leading to limited absorption of ultraviolet component of sunlight with higher energy consumption. In addition, some studies confused the adsorption and degradation. Therefore, to overcome the two major problems mentioned above, modification of Ti O2 to improve its catalytic performance was intentionally explored in this thesis.In the first part of the thesis, preparation of nanometer magnetic core Fe3O4 based on bayberry tannin(BT) was discussed. Magnetic Fe3O4 nanoparticles with well dispersion and controllable magnetic force were synthesized by utilizing bayberry tannin, a natural polymer with abundant phenolic hydroxyl, as template. The effect of experimental condition such as p H value, the amount of BT, reaction time, reaction temperature, and calcination temperature on magnetic force of the Fe3O4 prepared were explored. Moreover, structural property of the Fe3O4 synthesized were systematically characterized by TG, IR, XRD, BET, SEM, VSM, and so on. The experimental results indicate that the Fe3O4 nanoparticles prepared exhibit spherical and controllable magnetic force, with a maximum saturation magnetization of 81.08 emu/g when the mass ratio of tannin to iron and heat treatment temperature is 1: 1 and 800 ℃, respectively.In the second part of the thesis, preparation of Fe3O4/Ti O2 composite photocatalyst through supporting Ti O2 onto magnetic core Fe3O4 prepared in the first part was discussed. Fe3O4/Ti O2 catalyst with magnetic and catalytic property simultaneously, was prepared by sol-gel method assisted with solvent thermal crystallization, in which Ti O2 formed through the hydrolysis of butyl titanate and coated onto the Fe3O4. The structural property of the Fe3O4/Ti O2 catalyst was systematically characterized by ICP, XRD, SEM, UV-Vis, VSM, etc. Meanwhile, the effects of reaction condition, including temperature, the usage proportion between the reactants on the catalytic property were invested, methyl orange acting as the model pollutant in water. The experimental results show that, Fe3O4/Ti O2 photocatalyst exhibits excellent catalytic activity under ultraviolet light, which is close to that of P25 catalyst. Particularly, methyl orange degradation rate fell by only 7.1% after the 11 th repeated use, exhibiting favorable reusability. The main active radical for the degradation of methyl orange was determined as ·O2.In the third part of the thesis, in order to improve its catalytic property under solar light Ti O2 catalyst doped with three elements, eg., rare earth elements(cerium, neodymium) and non-metallic elements(fluorine), were prepared and denoted as Ce-Ti O2, Nd-Ti O2 and F-Ti O2, respectively. And a preliminary study was made on the preparation of Fe3O4/Nd-Ti O2 and Fe3O4/F-Ti O2 magnetic photocatalyst with different doping content. Three different kinds of Ti O2 photocatalyst and visible light responsive Ti O2 photocatalyst were prepared by sol-gel assisted with solvent thermal crystallization method using butyl titanate as precursor. The structural property of these catalysts were systematically characterized by XRD, SEM, UV-Vis. The results show that Nd-Ti O2 and F-Ti O2 the photocatalyst exhibit excellent catalytic activity under visible light, while Ce-Ti O2 and preliminary preparation of Fe3O4/Nd-Ti O2 and Fe3O4/F-Ti O2 photocatalyst exhibit low catalytic activity under visible light. Finally, The main active radical formed from the catalyst under solar light for the degradation of methyl orange was determined as ·O2 and ·OH. |
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