The Preparation Of Nano-TiO₂/Exfoliated Graphite Composites And Dealing With Azo Dye Wastewater Under Ultrasound Irradiation

This thesis reviews the structures and the characteristics of flake graphite,graphite intercalation compounds(GIC or expandable graphite) and expanded graphite(EG);it looks back the development of which graphite intercalation compounds(GIC) and EG has been prepared by natural flake graphite as raw materials for recent years;it introduces the application of EG in dealing with oil-water pollution and dyes wastewater.Meanwhile,it also reviews the preparation and the application of nano-TiO₂ in dealing with wastewater. Although EG has a strong and adsorptive capability and nano-TiO₂ possesses a strong and photoeatalytic degradation function,all of them just plays a single role in the process of treating water pollution.Thereby,it is necessary to prepare nanometer TiO₂/exfoliated graphite composites(the nanometer composites) which have the adsorption capability produced by the surface area and nanometer aperture of EG(nano-EG) and the photocatalysis capability of the nanometer particles of TiO₂(nano-TiO₂) synchronously.In the thesis,in order to simplify the preparation technology further,the former method (the preparation of the exfoliated graphite inserting nano-TiO₂),of which we have complete independent intellectual property,is used in the presence of the ultrasound irradiation. Therefore,the method to prepare the nanometer composites has been invented in the presence of ultrasound irradiation for the first time.Meanwhile,SEM,TEM and XRD have been also applied to characterize the structure,the mprphology and the relevant information of the nanometer composites,and they illuminate that the nanometer composites have the same structure and the morphology,comparing with our previous productions.In addition,it has proved that this new method can not only prepare the sulfur-containing nanometer composites but also the sulfur-free nanometer composites(Sulfur-flee meant that the reactants did not contain sulfur element in the process of preparation besides 320μm mesh of flake graphite contained itself).Azo dyes(methyl orange,active brilliant red X-3B,acid yellow 42^#,acid red 249,acid mordant brown RH) aqueous solution have been used as a model compound in the process of the research.Sulfur-free and sulfur-containing nanometer composites have been apart applied to investigate the removal ratios of the aqueous solutions.The experiment results have exhibited that the removal ratios of the aqueous solutions are influenced by the irradiation sources,the dosages of the nanometer composites,the initial pH values,the initial solution concentrations and the reaction temperatures.All of them have adsorption capability of nano-EG and the photocatalysis capability of nano-TiO₂,but they possess the different adsorption capability and photocatalysis capability under the above conditions.The experiment results have proved well that nanometer composites prepared under ultrasound irradiation have the strong adsorption capability and the strong photocatalysis capability;they have still proved that sulfur-free and sulfur-containing nanometer composites have different capabilities in the process of dealing with azo dyes aqueous solution. Meanwhile,the results also establish an experimental basis for dealing with azo dye wastewater actually.In the last chapter,we have discussed the mechanism of the adsorption and photocatalytic degradation produced by nanometer composites for azo dye molecules,and some significative conclusions are obtained as well as.In addition,the papers related studies have been reported on the foreign journal:Ultrasonics Sonochemistry(2007,SCI,IF:2.434) and the domestic central journal:Non-Metallic Mines.Main contents in this thesis:1.Nano-TiO₂/exfoliated graphite composites have been prepared by flake graphite as raw materials to prepare in the presence of ultrasound irradiation.2.The structure,the morphology and the relevant information of nano-TiO₂/exfoliated graphite composites have been measured by SEM,XRD and TEM.3.The adsorption and photocatalysis capability of the nano-TiO₂/exfoliated graphite composites have been investigated in azo dyes aqueous solutions.4.The mechanism of the adsorption and photocatalytic degradation produced by nano-TiO₂/exfoliated graphite composites for azo dye has been discussed.