Synthesis And Photocatalytic Properties Of Supported Titanate Photocatalysts

In this study, a sol-gel method has been used to synthesis two kinds of titanatespowder photocatalysts SrTiO3and Bi4Ti3O12, and the main preparation conditions wereoptimized. HZSM-5and SiO2spheres were used to synthesis supported catalysts, andthe key factors affecting photocatalytic activity were explored in order to obtainsuperior photocatalytic performance. The composite photocatalysts were deeplycharacterized through XRD, SEM, FT-IR, BET、BJH and UV-Vis measurements.Photocatalytic degradation of Reactive Brilliant Red under UV-light irradiation on thephotocatalytic materials was also examined. The main experiments are as follows:(1) Analysis of XRD spectrum shows that a minor phase of SrCO3impurity wasfound. The sol-gel method was adopted to disperse SrTiO3onto the surface of HZSM-5zeolite, while the HZSM-5was obtained by ion exchange from NaZSM-5byhydrochloric acid of different concentrations, and the effect of concentration ofhydrochloric acid on the degradation of Reactive Brilliant Red was also underinvestigation. The results show that the zeolite had a certain acid-resistant ability andstill kept the the original skeleton structure after modification and supported, The zeoliteand SrTiO3coexisted in the form of physical mixing. The specific surface area ofsupported photocatalyst significantly increased as compared to pure SrTiO3. With theincrease of concentration of hydrochloric acid, the crystallite size of SrTiO3becamesmaller, and specific surface area increased before they were reduced. Catalyst obtainedthe maximum specific surface area when the concentration of hydrochloric acid was0.3mol/L. At the same time, the absorption and photocatalytic degradation of ReactiveBrilliant Red X-3B reached the higest.(2) The HZSM-5was used as support which was treated with0.3mol/Lhydrochloric acid to prepare the supported χSrTiO3/HZSM-5.The supported catalystsshowed high specific surface area with a very broad pore size distribution, mainly in themesoporous and macroporous region. As the SrTiO3loading content gradually increased， the crystallite size of SrTiO3became smaller and specific surface area showed adecreasing tendency.(3) The supported catalysts with30%loading content were prepared underdifferent calcination temperature and their photocatalytic properties were also beenstudied. The results indicate that, a higher temperature was conducive to the formationof pure phase materials with lower organic and SrCO3impurities, but too highcalcination temperature lead to larger SrTiO3crystallite size and adverse effect onphotocatalytic performance. The optimum calcination temperature was determined to be700℃. The reaction rate of the supported photocatalyticst，which was calcined at700℃for3h with a loading content of30%, was significantly improved when compared withpure SrTiO3, The maximum degradation rate of Reactive Brilliant Red was54.6%,which is much higher than pure SrTiO3whose degradation rate was10.7%.(4) Bi4Ti3O12with pure phase and high crystallinity and χBi4Ti3O12/SiO2withdifferent loading content were successfully prepared. The shape of SiO2support wassphere with smooth surface whose particle size was almost less than2μm. TheBi4Ti3O12catalyst coated on the external surface of the SiO2after loading and a newchemical bond of Ti-O-Si formed between each other. Compared with pure Bi4Ti3O12,The catalyst with the optimal loading content of50%has higher reaction rate andphotocatalytic activity. The maximum degradation rate was58.5%on the50%Bi4Ti3O12/SiO2within30min and it was increased by16%when compared withpure Bi4Ti3O12whose degradation rate was42.5%(5) Ultraviolet-visible absorption spectra shows that both30%SrTiO3/0.3HZSM-5and50%Bi4Ti3O12/SiO2could effectively destroy azo conjugated system andnaphthalene ring structure of the Reactive Brilliant Red.