Sol-gel synthesis of suspensible titanium dioxide-hollow glass microsphere composites for photocatalytic degradation of Acid Red 1

Titanium dioxide was supported on hollow glass microspheres (HGM) via a sol-gel route to prepare xTiO(2)-HGM composites. The growth and aggregation of the anatase TiO2 crystals were restrained after supporting them. A thin layer of TiO2 was coated on the external surface of the hollow glass microspheres when the TiO2 content was not high. The absorption edges of the xTiO(2)-HGM composites moved to a shorter wavelength region with decreasing TiO2 content. The band gap energy of the TiO2 (3.21 eV) did not apparently change after loading on the hollow glass microspheres. The mesopores in the xTiO(2)-HGM composites were much larger than the pores in the TiO2 powders, and the pore size distribution in the xTiO(2)-HGM composites was broadened. The density of the xTiO(2)-HGM composites could be adjusted by altering the weight content of the TiO2. When the TiO2 content was more than 50% in the composites, the photocatalytic activity of the composites was very close to the activity of the TiO2 powders. The first order reaction rate constants were 0.00938, 0.0103 and 0.0121 min(-1) for Acid Red 1 degradation on the 30TiO(2)-HGM, 50TiO(2)-HGM and TiO2 powders.