Effect of surface hydrophobicity of TiO2-pillared clay on adsorption and photocatalysis of gaseous molecules in air

Three kinds of TiO2-pillared clay were prepared from different raw clays (montmorillonite, saponite and fluorine mica). Their surface hydrophobicities and performances in adsorption-photocatalytic degradation of toluene, trichloroethylene, ethylene and ethanol in a humid atmosphere, were investigated. The surface hydrophobicity of the pillared clay, estimated by adsorption isotherms of nitrogen and water, varied with the kind of the host clay. It increased in the order of saponite < montmorillonite < fluorine mica. The order of performance in adsorption of high hydrophobic substances like toluene and trichloroethylene on the TiO2-Pillared clay was consistent with that of the surface hydrophobicity of pillared clay. Enrichment of toluene and trichloroethylene by adsorption enhanced the rate of photocatalytic degradation on the pillared clay; the order of the catalytic activity also agreed with that of the surface hydrophobicity of pillared clay. The surface hydrophobicity of the TiO2-pillared clay did not exert much influence on either adsorption or photocatalytic degradation of low hydrophobic substances like ethylene and ethanol. (C) 2003 Elsevier B.V. All rights reserved.