The Studies On Preparation And Photocatalytic Activity Of Nanosized Titanium Dioxide / Diatomite Composites

Since the beginning of twenty-first Century, nanotechnology has entered a critical period of development and it has been obtained great achievements in many areas. Nano titanium dioxide has the nature of chemical stability, harmless, antibacterial and good photocatalytic activity properties, which makes it showed the value of strong application in the degradation of organic waste water and and the purification of air. However, the preparation of nano titanium dioxide have the difficulties of separation and recovery and the problem of low catalytic efficiency, which limits the development of applications. Diatomite can well capture the photogenerated holes to inhibit the invalid composite of the electron hole pairs which have light catalytic effects. It is due to the special porous structure of the diatomite and a large number of silicon hydroxyl groups on it. In order to expand the scope of application, we can make full use of high specific surface area on the diatomite to adsorbent the harmful substances for the light degradation of nano titanium dioxide effectively if the nano titanium dioxide loaded on the surface of diatomite.This method attempts to use titanyl sulfate, diatomite and barium hydroxide as the raw materials, stepwise hydrolysis precipitation is used to prepare the needed photocatalytic composite material. The method has the advantages of simple operation and easy to control the production conditions. It can eliminate the washing process of inorganic salt in the traditional process, while also eliminating reunion problems of the nano titanium dioxide particles due to the roasting.According to the research content, this thesis is divided into three parts:1. The preparation of nano titanium dioxide/diatomite composites. Based on titanyl sulfate, diatomite and barium hydroxide as main raw materials, it attempts to adopt the step hydrolysis precipitation method to prepare photocatalytic composites in this paper, while barium sulfate required in coating is also prepared in the process. The samples are characterized by SEM, XRD, EDS and other instruments. The optimal preparation conditions are obtained through the degradation experiment of composite materials. It shows that the bestphotocatalytic property is refluxed under acidic conditions for 75 min without calcination, the quality of titanium dioxide and diatomite is 1:3 after the study of a series of contrast.2. The studies on photocatalytic degradation by nano titanium dioxide/diatomite composites. The photocatalytic properties of nano titanium dioxide/diatomite composites are studied with acid red 3R as waste water under solar light irradiation, the effects of various conditions of dye to the catalytic effect in the system is discussed at the same time. The experimental process is that adding a certain amount of composite materials prepared in each500 m L beaker, which filled with acid red 3R dye with 200 m L concentration. Each beaker is placed in the sun with a magnetic stirrer for photocatalytic experiment. The samples are taken at a certain time and measured its degradation rate after high speed centrifugation. It can be found that the composite material exhibit better performance with longer illumination time and lower concentration of dye when the p H value of the solution is fixed at 3. Acid red 3R dye is decomposed into H2 O and CO2 and other simple molecules by nano titanium dioxide of composite materials, rather than simply adsorption on diatomite through the detection of infrared spectra.3. Application of nano titanium dioxide/diatomite composite materials in coatings The coating of interior wall has light degradation function after dopping the self-made nanometer titanium dioxide diatomite composite, which lays a solid foundation for the research of functional coating. The photocatalytic effect is the best in the experiment when using the new type of coating which using composite instead of the original paint formula in 2/3 solid filler.The results of the experiment shows that the new coating degradation of acid red 3R rate can reach more than 90% under the irradiation of sunlight.