Photocatalytic Properties of Titania Pillared Clays by Different Drying Methods.

Photocatalysts based on titania pillared clays (TiO2 PILCs) have been prepared through a sol-gel method. Different drying methods, air drying (AD), air drying after ethanol extraction (EAD), and supercritical drying (SCD) have been employed and found to have significant effects on the photocatalytic efficiency of the resultant catalysts for the oxidation of phenol in water. Titania pillared clay (TiO2 PILC) obtained by SCD has the highest external and micropore surface area, largest amount and smallest crystallite size of anatase, and exhibited the highest photocatalytic activity. Furthermore, silica titania pillared clay (SiO2-TiO2 PILC) after SCD, titania coated TiO2 PILC (SCD) and SiO2-TiO2 PILC (SCD) were synthesized to study the key factors controlling the photocatalytic activity. It is concluded that the dispersion of nanometer-sized anatase on the surface of the PILC particles and the suspensibility of the particles are the most important factors for high photocatalytic efficiency. Copyright 1999 Academic Press.