Preparation And Characterization Of TiO₂/SiO₂Composite Aerogel

The aim of this work is to synthesize TiO2/SiO2composite aerogel via an ambient pressure drying process. The composite aerogel not only present the photocatalysis of TiO2but also possess the high sorption of the porous materials, which can overcome the problem that the network of pure TiO2aerogel is weak and the TiO2powder is hard to recycle in the practical application.Using cheap titanium tetrachloride and waterglass as raw materials, TiO2/SiO2composite aerogels were prepared via an ambient pressure drying process, by using Trimethylchlorosilane/Ethanol/Hexane solution to modify the sol-gel-derived TiO2/SiO2composite wet gel. The microstructure, morphology and pore properties were studied by SEM, TEM, XRD, FTIR and BET measurement. The properties of adsorption and photocatalytic degradation of rhodamine B were analyzed by spectrophotometer. The results indicate that the obtained TiO2/SiO2composite aerogels, which prepared at ageing temperature80℃, ageing time for just white and n(Ti):n(Si)=4:1, exhibit a porous structure, with the specific surface area1076m2·g-1and pore volume4.96cm3·g-1after dried at150℃. Moreover, the aerogels still show high porosity after calcined at550℃, with specific surface area856m2-g"’and pore volume3.46cm3·g-1. The results of adsorption and photocatalytic degradation of rhodamine B show that TiO2-SiO2composite aerogels have both good adsorption and photocatalytic properties. The synergistic adsorption/photocatalysis activity of TTiO2/SiO2composite aerogels were better than pure SiO2aerogels and pure anatase TiO2powder, achieved97%. Additionally, the adsorption/photocatalytic degradation rate was still up to89%after being used four times.Using Tetrabutyl titanate and waterglass as raw materials,TiO2/SiO2composite aerogels were prepared by adsorption method via an ambient pressure drying process. The results indicate that TiO2/SiO2composite aerogels exist in the form of amorphous SiO2and anatase TiO2after calcined at550℃. SiO2had suppressed the crystal transformation of TiO2. The obtained TTiO2/SiO2composite aerogels exhibit a porous structure, with the specific surface area583m2·g-1and pore volume2.85cm3·g-1.The synergistic adsorption/photocatalysis activity of TiO2/SiO2composite aerogels were better than pure SiO2aerogels and pure anatase TiO2powder. The adsorption/photocatalysis degradation rate of rhodamine B achieved96%.