Preparation And Properties Of Photocatalytic TiO₂ Coating

At present,the air pollution in our country has not been effectively controlled,and particulate pollutants in the air are tend to adhere to the external walls of buildings and cause smudges,which affects the appearance.The photocatalytic cement-based material has drawn significant attention.Anatase TiO₂ crystallizes under the treatment of water vapor,and steam curing technology is a very important curing technology in the field of cement-based materials.Considering that the treatment of water vapor is similar to steam curing,steam curing can be used to replace the treatment of water vapor to crystallize TiO₂.In this work,anatase TiO₂ was prepared by steam curing under the different environmental conditions,and photocatalytic cement-based material was successfully prepared.The composition and properties of anatase TiO₂ and photocatalytic cement-based material were analyzed by XRD,photocatalytic performance tests and self-cleaning performance tests.And the main research results are as follows:（1）Sol-gel technology and steam curing technology were combined to prepare TiO₂ with anatase structure at low temperature,and the effects of sol-gel process parameters and steam curing process parameters on the crystallinity of anatase TiO₂were studied.p H values,acid catalysts and steaming temperatures affect the crystallinity of anatase TiO₂.When the p H value decreases,the crystallinity of anatase TiO₂ increases.Strong acid catalyst is beneficial to the crystallization of TiO₂ at lower p H values.Within a certain range,the higher the steaming temperature,the better the crystallinity of anatase TiO₂.（2）Sol-gel technology and steam curing technology were combined to prepare anatase TiO₂ in alkaline environment,simulated cement environment and real cement environment,the crystallinity of anatase TiO₂ at different environments was studied as well.The crystallinity is better when water content is low,and the crystallization of anatase TiO₂ isn’t inhibit by the cations in the preparation process,but the impurities in the real cement environment reduce the crystallinity of anatase TiO₂;（3）The photocatalytic performance of anatase TiO₂ prepared under three environments was tested,the photocatalytic activity of anatase TiO₂ prepared under alkaline environment is the highest,the degradation rate of Rh B solution is 98.6%,the degradation rates of anatase TiO₂ prepared in the other two environments are 88.2%and 73.9%,respectively.This is mainly because the cations or impurities in the preparation environment adversely affect the photocatalytic activity of anatase TiO₂;（4）Sol-gel technology and steam curing technology were combined to prepare photocatalytic TiO₂ coating on the cement substrate,the crystallization of anatase TiO₂isn’t inhibited by the hydration process of cement during steam curing.The photocatalytic performance of the photocatalytic cement-based material was tested,it is found that the degradation rate of Rh B solution is 97.9%,the degradation rate includes the contribution of photocatalytic activity and adsorption.Self-cleaning performance of the photocatalytic cement-based material is tested,the self-cleaning efficiency of the photocatalytic cement-based material reached 56%after that the cement was exposed to ultraviolet light for 12h.