The influence of the interfacial properties of composite catalyst material on the photocatalytic conversion of TiO_2 layer silicates

Abstract

Solid-gas and solid-liquid interfacial properties of titanium dioxide/layer silicate composite sorbents were studied by sorption experiments and the photocatalytic properties were also investigated.The photocatalyst TiO 2 was prepared by the sol-gel method and the sol obtained was used for heterocoagulation of Namontmorillonite at several different mass ratios, yielding supported photocatalysts of various compositions. The TiO 2 content of the samples ranged from 20 to 75 wt%. The specific surface areas of the samples, determined by nitrogen adsorption, ranged from 120 to 290 m 2 /g. The catalytic properties of TiO 2 /montmorillonite composites were tested by photooxidation of dichloro acetic acid (DCA). The specific surface area and the porosity exert a major influence on the photocatalytic efficiency through the interfacial layer properties. The rate of photo-oxidation of DCA depends strongly on the surface accessibility of the intermediates and the specific surface area calculated from gas and liquid mixture adsorption data. The conversion data of DCA presented show that the photocatalytic efficiency of TiO 2 can depend significantly on the accessibility of different molecules to the TiO 2 nanocrystals embedded in the layer silicate support in confined space.

A Kinetic Study on Photocatalytic and Sonophotocatalytic Degradation of Textile Dyes

“…The hole can subsequently react by electron transfer with a substrate to form a radical species or hydroxide (water) to form hydroxyl radical. In condensed oxygenated aqueous media the surface of TiO 2 is completely hydroxylated and upon photoexcitation generates hydroxyl radical in an adsorbed state [10][11][12][13].…”