Preparation Of Titanium Dioxide Nanocomposites And Their Photocatalytic Degradation Of Organic Compounds

In recent years, photocatalytic degradation technology is very popular research direction. Photocatalytic technology can make all kinds of organic and inorganic pollutants in wastewater and waste gas mine into our fleet and H₂ O completely, and has low energy consumption, mild reaction conditions, less secondary pollution, the advantages of the catalyst can be reused, thus became a focus of environmental technology research. TiO₂ is a kind of low cost, green environmental protection, light absorption ability of the semiconductor optical catalyst, can use sunlight for photocatalytic degradation of organic and inorganic macromolecule for small molecule inorganic pollutants such as CO₂ and H₂ O. Thus Ti O₂ is widely used in pollutant treatment, but because of the forbidden band width of TiO₂ is larger, 3.2 eV, only absorbs less than 380 nm wavelength ultraviolet energy, but uv light accounts for only about 5% in the sun light, visible light proportion is about 50% in the sunlight, TiO₂ can’t use this part of the sun’s energy, TiO₂ light response while keen, but the utilization efficiency of sunlight energy is very low. And TiO₂ light excitation produced by light electronic-hole for easily happened compound, reduce the photocatalytic efficiency of Ti O₂. Recent scientific research workers try to improve the performance of the TiO₂, improve main method with precious metals complex and ion doping, formation heterostructure nano composite photocatalytic materials and so on, so the TiO₂ photocatalytic performance has been greatly improved. In this thesis, the organic polluants are degraded by the prepared grapheme/TiO₂ and Cd S/ TiO₂,while the visible decline in methyl orange solution as a model reaction,this is used to investigate the different effects constituting the composite material on the photocatalytic activity,pecific research contents and conclusions are as follows:（1）2 hydroxy acid in complex titanium acid ammonium（TALH） is used as the titanium source, oxidized grapheme is used as carrier, graphene/TiO₂ photocatalyst nano composite material was synthesized by hydrothermal method, and by changing the amount of urea to control the graphene/TiO₂ photocatalyst nanocomposite particles size, morphology and catalytic effect. By using the preparaed graphene/TiO₂ photocatalyst nanocomposite for photocatalytic degradation of methyl orange, and the performance characterization of the XRD and SEM of the sample, when the dosage of the urea is 9.0 g, the photocatalyst nanocomposite photocatalytic effect of graphene/TiO₂ is best. And by controlling the content of urea to adjusting anatase and plate titanium ore the proportion of these two kinds of crystal shape.With XRD, UV-Vis, method of XPS, SEM characterization of synthesis of samples, and test the different proportions of twin TiO₂/ reduction of graphene oxide photocatalytic materials in the simulated sunlight in the activity of methyl orange（MO）. The test results show that the urea content is 0.6 g, synthesis of composite materials for anatase TiO₂/reduction of graphene oxide（TiA100/g）, when the urea content increased to 42 g, products for plate titanium ore TiO₂/graphene oxide（TiB100/g）. And add 9.0 g of products generated by the anatase urea（35%）, plate titanium ore accounted for 65%（TiA35B65/g）, the ratio of composite materials in the degradation of methyl orange test showed the best activity. SEM showed that Ti A35B65 is globular anatase nanoparticles and stick plate titanium ore mixture of nanoparticles longing on the G.（2） This experiment with nonionic surfactants P123 as a template, using sol-gel method with different content of CdS of mesoporous TiO₂ nanocomposites. Using X-ray diffraction（XRD） phase of the location of the characteristic peak identification materials; Using scanning electron microscope（SEM） to observe microstructure of ions. Research shows that the preparation of CdS/TiO₂ crystal type of TiO₂ materials mainly anatase with high catalytic activity, and has the mesoporous nanoparticles are structure, these phenomena indicate that mesoporous CdS/TiO₂ nanomaterials preparation of success. Methyl orange was used to simulate organic wastewater degradation experiments, found that 2% of mesoporous CdS/TiO₂ nanomaterials xenon lamp exposure after 75 min of the degradation of methyl orange efficiency reached 87.5%. Its catalytic efficiency compared with the pure Ti O₂ and CdS catalytic efficiency improved significantly. Using the method of gel and sol, hydrothermal synthesis method to get the CdS/TiO₂ materials, high temperature calcination make its crystallization. Using TEM, XRD, UV-Vis analysis product structure analysis. Results show that the CdS is located inside TiO₂, form a mesh structure, it is because of the reticular structure function and TiO₂ due to space limitations effect. Photocatalytic degradation of methyl orange experiments show that the CdS/TiO₂ photocatalyst can be repeatedly used, it is not a simple adsorption, so Cd S/TiO₂ photocatalyst can be used in the degradation of organic waste water in nature. By the effect of amount of CdS on photocatalytic degradation of CdS/TiO₂,we knew that photocatalytic degradation effect is best when the CdS content is 2%. Possible explanation is that the Cd S dispersed in the interior of the TiO₂ fully, thus electronic-hole transfer rate and TiO₂ catalytic efficiency of photocatalys is improved.