Preparation and properties of TiO2/montmorillonite composites

Abstract TiO 2 /montmorillonite composites were prepared by reaction of montmorillonite with a TiO 2 sol formed by hydrolyzing titanium iso-propoxide, at 50–80 °C. The composites showed expanding and broadening of the basal reflections of montmorillonite indicating a partial intercalation of the smaller colloidal TiO 2 particles and increased disorder. The reaction temperature affected largely the amount of TiO 2 hydrolyzed and the resulting pore sizes. Both properties increased with increasing reaction temperature; the TiO 2 content from 24.2 to 46.6 mass% and the average pore size from 2 to 20 nm. The colloidal TiO 2 particles consisted of anatase up to 1000 °C without transforming into rutile. The growth of the TiO 2 particles was suppressed by the montmorillonite particles. Adsorption of methylene blue (MB) was higher in the composite prepared at 80 °C than in that at 50 °C because of the larger pore size. Photocatalytic decomposition of 1,4-dioxane by the composites was higher than for pure anatase due to the synergy effect of adsorption for 1,4-dioxane and photodecomposed intermediates by montmorillonite and its photodecomposition by TiO 2 .