Study On Preparation And Photocatalytic Properties Of Non-metal Elements-doped Titania Hollow Microspheres

In this thesis, We focuse on the limitations of practical application of titanium dioxide material. Preparation of titanium dioxide hollow microspheres with hollow structures. Such titanium dioxide hollow microspheres overcome the defects, which the thermal stability reduced with the increase of surface area, in order to got compatible high stability and high surface area, and enhance the usefulness of titanium dioxide. Meanwhile, according to the photocatalytic theory, We doped the prepared titanium dioxide hollow microspheres, with non-metal elements, increased the utilization of sunlight, and improved the performance of photocatalytic degradation of formaldehyde .Monodisperse polymer microsphere preparation method is simple, the product particle diameter and distribution can be controlled, and easy to surfacal functional. We use the P(St-HEA) microspheres as template, tetrabutyl titanate as precursor, combine the sol-gel method, prepared P(St-HEA)/TiO₂ core-shell composite microspheres. Then remove the template by calcination, finally got the anatase titanium dioxide hollow microsphere. After all, use the the nitrogen, sulfur elements as non-metallic elements doped the prepared titanium dioxide hollow microspheres. Test the photocatalytic properties of titanium dioxide hollow microspheres by photo- catalytic experiments.The main research contents and conclusions are listed as following parts:1 . P(St-HEA) microspheres was prepared by Free emulsion polymerization method. Studied the Influence on monomer conversion rate of reaction temperature, reaction time, and the influence on the final microsphere size and size distribution of the initiator dosage. The results showed that the reaction temperature is 85℃, after reacting 2h added the comonomer HEA, and the suitable total reaction time was 5h. When the amount of initiator in water was 0.3wt%, the monomer conversion was highest to 94.1%. And, with the amount of HEA in the monomer increased, P(St-HEA) microspheres particle size increases, and the size-dispersion is superior.2.P(St-HEA)/TiO₂ core-shell composite microspheres was prepared by sol - gel method. P(St-HEA) microspheres with particle size of 230nm was used as template. And Tetrabutyl titanate was used as sol - gel precursor. Then remove the template by calcination, anatase TiO2 hollow microspheres was prepared. TiO2 hollow microspheres with particle size of 210nm, and the shell thickness is about 10nm. Non-calcined TiO2 hollow microspheres, the shell is loose, no-crystallize formed. During the calcination process, template lost leaded to volume shrinkage. At the same time, the shell crystallized to compact crystal form. With these two roles, TiO2 hollow microspheres particle size reduced, but did not influence the particle size and uniformity particle size distribution. XRD results show that the crystalline titania hollow spheres can be controlled by adjusting the calcination temperature. Obtained anatase titanium dioxide when the calcination temperature is 500℃. Obtained rutile titanium dioxide when the calcination temperature is 800℃.3.Mixture of TiO₂ hollow microspheres and a certain amount of carbon powder was completely soaked in a hydrazine hydrate (H₂NNH₂·H₂O), and then the closed in the container, microwave irradiation on the mixture. At the same irradiation time, the N-doped titania hollow spheres was significantly higher photocatalytic properties than non-doped titania hollow spheres. XRD results show that the N-doped titania is anatase crystal from. XPS analysis showed that the N3- doped into crystal from, and the N content was 1.03%.Microwave radiation doping did not change in the crystal from of titanium dioxide. When the microwave irradiation time was 30min, the N-doped titanium dioxide has the best photocatalytic properties.4.S-doped TiO2 can be prepared by the sol-gel method, using thiourea as the source of sulfur. XPS and XRD analysis indicated that the S-doped into the titanium dioxide crystal form, and there is only a little local distortion existed in S-doped TiO2. Doping on titania hollow microspheres showed little effect on morphology and particle size and size distribution of the TiO2 hollow microspheres. XRD analysis showed that the incorporation of sulfur, changed the titanium dioxide lattice structure, and change some parts of the titanium dioxide crystal form from Anatase to Rutile. By XPS analysis indicates that sulfur is S⁴⁺ form in titanium dioxide doped crystal phase, with S content of 1.44wt%. 5.Color liquid were mixed of 4.00ml acetylacetone color reagent and 4.00 ml formaldehyde solution. The heating temperature is 100℃, and the heating time was 10min. The experimental photocatalytic wavelength was 414 nm. The performance of photocatalytic degradation of formaldehyde results show that the doped titania hollow spheres was superior photocatalytic activity of undoped titania hollow spheres. And photocatalytic properties of both are higher than titanium dioxide powder (P25) of the good. Catalyst amount, time and catalyst catalytic photocatalytic properties of the environment. In doped titania hollow spheres 120mg, after 120min under ultraviolet irradiation, the degradation rate of formaldehyde up to 79.4%.