Study On Preparation And Properties Of TiO₂/SiO₂Composite Photocatalysts

At present, TiO₂/SiO₂composite photocatalysts were mostly prepared from expensive butyltitanate and ethyl silicate. Using inorganic titanium salt and silicate as material, the cost ofpreparation can be reduced. Liquid phase hydrolysis method has the advantages of shortpreparation period, simple process and convenient operation. The compound of SiO2can notonly improve the adsorption properties and thermal stability of photocatalyst, but also make thephotocatalyst separated from the water easily.In this paper, the TiO₂/SiO₂composite photocatalysts were prepared from inorganic titaniumsalt and silicate by liquid phase hydrolysis-calcination method. The effects of titanium source,ratio of titanium to silicon, pH value of hydrolysis, the sort of alkali, the temperature and time ofcalcination, the dosage of titanium on the photocatalytic activity of the photocatalysts werestudied during the photodegradation of methyl orange in aqueous solution.Compared with the calcination method, the hydrothermal method has the advantages ofuniform reaction and crystalline phase transformation at low temperature, so using liquid phasehydrolysis-hydrothermal method to prepare TiO₂/SiO₂composite photocatalysts. And theappropriate hydrothermal temperature and time were determined.Property test analysis showed that, TiO₂/SiO₂composite photocatalysts prepared by liquidphase hydrolysis-calcination method and liquid phase hydrolysis-hydrothermal method wereboth nanometre spheric particles which disperse evenly. TiO₂/SiO₂have large surface area,outclass surface area of the best photocatalyst P25at present and single TiO2, and form anataseTiO2mostly. The compound of SiO2inhibited the growth of TiO2crystal particles and crystalphase transformation into adverse effectively, at the same time improved the thermal stability ofTiO2.After contrasting and analysing with single TiO2and P25photocatalyst, the photocatalyticactivity of TiO₂/SiO₂composite photocatalysts prepared by liquid phase hydrolysis-calcinationmethod and liquid phase hydrolysis-hydrothermal method were both higher than single TiO2photocatalysts, and almost the same as P25.