Preparation of macro-sized macro-mesoporous TiO₂-SiO₂ photocatalyst and its application in dye degradation

The macro-sized macro-mesoporous SiO₂ was prepared by using a pillared epoxy resin macroporous polymer as the template and it was used as support to prepare macro-mesoporous TiO₂ nanocrystalline-SiO₂ composite through an in situ hydrolysis of tetrabutyl titanate and a subsequent calcination at high temperature. The macro-mesoporous TiO₂-SiO₂ samples were characterized by SEM, TEM, XRD, FTIR and N₂ adsorption-desorption. Using azophloxine as a simulated pollutant, the photocatalytic activity of the macro-mesoporous TiO₂-SiO₂ was studied under the sunlight irradiation simulated by Xenon lamp under different conditions. The results show that the macro-mesoporous SiO₂ has 3D continuous pass-through macropore structure and its pore wall is continuous SiO₂ nano-film. TiO₂ nanocrystallines, in the form of nano-film, in situ grow uniformly on both sides of the nano SiO₂ film, and abundant mesopores were observed on the pore wall of the obtained macro-mesoporous TiO₂-SiO₂ composite. The macro-mesoporous TiO₂-SiO₂ photocatalyst exhibits the best activity for photocatalytic degradation of pollutant from the macro-mesoporous TiO₂-SiO₂ composite containing 15.7wt% of TiO₂ calcined at 600℃, under the conditions of azophloxine concentration 10 mgL^-1 and pH of 3. The macro-mesoporous TiO₂-SiO₂ photocatalyst also has good reusability.