Study On Peptizing Preparation And Application Of TiO₂ Nanocrystalline Sol

TiO₂ is a kind of semiconductor photocatalysts with excellent properties such as high efficiency,low energy consumption,innocuity,good stability,which makes it have important applications in renewable energy and environment fields.TiO₂ thin films is researched widely as it can overcome the shortcomings of TiO₂ powder that is easy to agglomerate and difficult to recycle when being applied on a variety of substrate,.In recent years,with the increasing demand of application in surfaces of materials which do not resist heat or the surface area is too large to heat,such as engineering plastics,organic coatings and so on,It is becoming hot to prepare TiO₂ thin film at low temperature.In this paper we researched the low temperature preparation and application of TiO₂ thin film,put forward the research programe of preparing TiO₂ thin film by nano-crystal TiO₂ sol,prepared TiO₂ sol with anatase using low-cost inorganic salts TiOSO₄ as precursors by colloidal chemical method,designed the composite system of nano-crystal TiO₂ sol/vinyl acetate-acrylate latex,nano-crystal TiO₂ sol/organosilicon sol,so as to solve practical application problem such as ununiformity and poor adhesion of film prepared by pure nano-crystal TiO₂ sol.Specific major tasks include the following aspects:(1) Study on preparation and optimization of TiO₂ nanocrystalline solUsing low-cost TiOSO₄ as precursors,preparation of acid and neutral TiO₂ sol were studied by peptizing method The impact of preparing conditions on crystallinity degree, particle size.photocatalytic efficiency of TiO₂ sol were emphatically investigated. Optimized preparing conditions of acid TiO₂ sol are as follows:peptizing temperature and time were 60℃and 6h separately,adding amount of HNO₃ was H⁺:Ti⁴⁺=4.Optimized preparation conditions of neutral TiO₂ sol are as follows:peptizing temperature and time were 65℃and 4h separately,adding amount of H₂O₂ was H⁺:Ti⁴⁺=16 By comparing acid and neutral TiO₂ sol,it is known that the stability and photocatalytic activity of acidic TiO₂ sol are better than that of neutral TiO₂ sol.(2) Study on preparation and properties of vinyl acetate-acrylate/TiO₂ composite film The acid TiO₂ nanocrystalline sol was added into vinyl acetate-acrylate latex.The impact of TiO₂ content in the compound system on the structure and properties of the film were emphatically investigated.The results show that the composite coating solution has high stability and excellent film forming property.With the increase of TiO₂ sol addition,the amount of TiO₂ particles in the surface of the film increases,which leads to the increase of roughness of the film.When the concentration of the TiO₂ sol increases from 0.1 mol/L to 0.3mol/L,decomposition rate of the composite film to rhodamine B increases from 53.8%to 78.8%and the contact angle decreased from 66°to50°after the UV irradiation.(3) Study on preparation and properties of organosilicon/TiO₂ composite filmEthanol based acid TiO₂ nanocrystalline sol was prepared by colloidal chemical method and then added in organosilicon sol.On this basis,research on preparing films on the surface of polycarbonate sheet(PC sheet) by composite coating solution were carried out.The adding amount of TiO₂ sol,concentration of TiO₂ sol and coating layers of the composite fihn were mainly studied.The results show that when the adding amount of TiO₂ sol is 40wt%,fihn forming property of the composite coating solution is well.When the concentration of the TiO₂ sol is 0.3mol/L,photocatalytic performance of the composite film is the best,and decomposition rate of the composite film to rhodamine B was 74.4%.When the coating layer was two,it guarantees much TiO₂ particles on the PC sheet,and the film is uniformity,less crack and has sufficient light transmittance.