Synthesis and structural and photocatalytic properties of TiO2/montmorillonite nanocomposites

TiO2 was prepared by sol–gel method and the sol obtained was used for heterocoagulation of Na-montmorillonite at several different mass ratios, resulting in nanocomposites of various compositions. The TiO2 content of the samples ranged from 20% to 75% (m/m). Heterocoagulation was performed using a strongly acidic (pH = 1) as well as a weakly acidic (pH = 4) Ti(OH)4/TiO2 sol. X-ray diffraction measurements of the samples reveal that in the course of composite formation, TiO2/montmorillonite intercalation structures containing the anatase phase of TiO2 were formed. The specific surface areas of the samples determined by nitrogen adsorption ranged from 120 to 290 m2/g. TiO2/montmorillonite composites prepared at pH = 1 have higher specific surface areas than those prepared using the sol with pH = 4. The catalytic properties of TiO2/montmorillonite composites were tested in the photooxidation of phenol. The TOC data presented show that the photocatalytic efficiency of TiO2 can be significantly enhanced by intercalation in montmorillonite support.