The Research Of Preparation Of TiO₂/Fe₂O₃ Composite Film And Photocatalytic Degradate Organic Waste Water

The nano-film system of TiO₂ and oxides of iron have been studied in this thesis. A composite film system of TiO₂/Fe₂O₃ has been prepared successfully on ordinary slide, as well as its reaction mechanism and photocatalytic degradation effect of Methylene blue have been disscussed after researching the influences of a series of factors, such as the number of coating,temperature and time of roasting,different light sources,different targets and their initial concentration,light time,reaction atmosphere and doping. The main research and conclusion are as follow:1,Prepare TiO₂ films on common slide surface by sol-gel and dip-coating method. That means blend tetrabutyl titanate,ethanol,water,nitric acid (1mol/L) together at volume ratio of 3: 15 :1:5 and add appropriate quantity of glacial acetic acid firstly, then roast the compound at 550℃for 2 hours, finally we can get compound mineral phase nano TiO₂ whose crystal length ranged from 5 to 10nm. Hydrolyze trivalent ferric and alkali completely mingle at pH 2.1 and stir constantly, they will convert into hydrated ferric oxide after oscillated in water bath of 60℃for 48 hours. Then coat five films on the pretreated slide and roast at 350℃for one hour,α- Fe₂O₃ whose crystal length ranges from 20 to 60nm will be obtained. We will finally get TiO₂/Fe₂O₃ composite nano-films if the nano TiO₂ films peviously prepared are roasted at 350℃for one hour after coated five layers of ferric oxide films. TEM indicates that rod-like hematite crystal have attached to the round-like titanium dioxide crystal with clear lattice stripes.2,The degradation rate of Methylene blue (5mg/L) is 78% which is degraded by pure TiO₂ film catalyst in the condition of UV and constant aeration for one hour. The industrial waste water DMSO can be degraded under UV for 6 hours at the rate of 86%. The film modified by doping iron has higher photocatalytic degradation rate. The photocatalytic degradation rate by pure TiO₂ film is nearly zero under xenon.(We only use one piece of film slide whose coating weight is no more than 0.01g to degrade waste water in this thesis, and the volume of MB is 10mL with concentration of 5mg/L if there isn't any specific instruction.)Pure Fe₂O₃ film catalyst can degrade Methylene blue with concentration of 1mg/L after illuminated under UV for two hours without any acid,alkali,catalyst or air at the rate of 68%, which is a little lower than that of pure TiO₂ film catalyst. The degradation rate of Methylene blue with concentration of 5mg/L is 55% after illuminated under xenon for 2 hours, and the degradation rate for 10 hours is 75%.3,TiO₂/Fe₂O₃ composite films catalyst can degrade Methylene blue with concentration of 5mg/L after illuminated under UV for 3 hours without any acid,alkali,catalyst or air at the rate is 60%, which is lower than that of pure TiO₂ films. The degradation rate of Methylene blue with concentration of 5mg/L by the composite films is 65% under xenon for 2 hours, which is higher than Pure Fe₂O₃ film and have expanded the range of light response area of TiO₂. We can separate the electric charge effectively with the help of the difference between two different semiconductor's energy level, and as a result we can increase its quantum efficiency and expand the inspire wavelength to its maximum. The degradation rate of MB is 80% after illuminated under the sun for 10 hours, which is higher than that of pure Fe₂O₃ film.