| Water environmental protection is an issue that widespread concern in human society. Experts estimate that a quarter of the regional will long-term lack of water from the beginning of the next century.Our country is also lack of fresh water,especially the wastewater with high concentration of organic has been caused a serious threat to our precious water resources with the rapid development of the national economy in recent decades.So,Its imperative to regulate the organic wastewater in this environmentally-friendly appeal era. But there are some shortcomings such as energy consumption,secondary pollution,incomplete degradation have been hindered the progress of water governance.The Photocatalytic activity of TiO2is a very promising method to regulate the sewage at present.The TiO2films have gradually become the focus of which scholars study because of the long life cycle and easy to recover.A dense titania film can generate from the titanium substrate by micro-arc oxidation method. This approach not only simplifies the complex preparation process of titanium film, but also improve the photocatalytic activity because of the special surface pore structure.In this work, MAO technology was applied to fabricate films on Ti itself in Na2SiO3-Na2WO4solution by constant positive pulse current modes. The TiO2films with different thickness and morphology were obtained by changing the current density, the relationship between the current density and the morphology and thickness were analyzed.In order to obtain the different crystal ratio,the TiO2films were heat-treated at different temperatures, then analyzed the relative content of the anatase and rutile. To get Zn/TiO2composite films, Zn was adulterated in TiO2films by impregnation method, the effect of Zn to spectral response were analyzed by UV-Vis diffuse reflectance,and the factors such as film conditions, type of grain and Zn-doped were analyzed.At last,certain bias was imposed at the same time when photocatalytic to research the catalytic effect of TiO2film, and establish the catalytic dynamics.The results shows that the voltage which changes with time is divided into two parts,It grow rapid at the first five minutes and then stable at the last15minutes, the morphology of the surface was porous, the best surface condition is the sample that with11A/dm2current density. The film mainly composed of dense layer and porous layer,the main elements from the inside to the outside showing the gradient distribution. All of The samples with three different current density are showing catalytic characteristics, especially the samples with11A/dm2current density,the degradation rate of methyl orange achieve25%within2hours.The transition temperature from anatase to rutile is about600℃-650℃.All of the samples with500℃,550℃,600℃,650℃heat treatment are showing catalytic characteristics, but with the rutile phase generation, the degradation rate of methyl orange is reducing from25%to16%.The addition of Zn is had no significant effect to the surface morphology and physical properties, but it can broaden the absorption spectrum of titanium dioxide, make the red shift of the absorption edge move nearly20nm. The stability of the film is still good afer degrade the methyl orange10times, power assisted photocatalytic significantly improve relative to the film that not doping zincWith the increase of the applied potential, the photoelectrocatalytic degradation rate will enhance. When the bias voltage increased from0.6Vto1.2V,the degradation rate of methyl orange increased from25%to60%within120minutes.When the applied bias exists, the photoelectric kinetics of catalytic reaction showing zero order reaction. When the methyl orange concentration are5mg·L-1and10mg·L-1, the photoelectric kinetics of catalytic reaction showing f0irst-order reaction. When the methyl orange concentration are15mg·L-1and20mg·L-1, the photoelectric kinetics of catalytic reaction showing zero-order reaction. |
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