Mahnaz karbassi - Graduate student
Ali. Nemati - Professor, Materials science & Engineering Department, Sharif University of Technology, Tehran, Iran
Maryam Hosseini Zori - Professor, Department of Inorganic Pigments and Glazes, Institute for Colorants, Paint and Coatings, Tehran, Iran.

Titanium dioxide (titania) particles were prepared by a water-in-oil emulsion system, and studied for the photodecomposition property of methylene blue. Microemulsion (ME) consisted of water, cyclohexane and a anionic surfactant such as (AOT). The smallest diameter of the particles was 70 nm in the system of cyclohexane with surfactant when the molar ratio of water to surfactant was 5. The effect of the process parameters (water/surfactant ratio, temperatures) on the final characteristics has been investigated, in terms of structural phase and particle size. Titania particles prepared in this condition were collected as amorphous powder, and converted to anatase phase at less than 500°C, which is lower than the ordinal phase transition temperature. In addition, the size of particles increases with an increase of water/surfactant ratio. The titania nanopowders were characterized by means of X-ray diffraction and SEM, TEM, FT-IR, and DTA. The titania calcined at 5000C shows the highest activity on the photocatalytic decomposition of methylene blue.

microemulsion, nanopowder, titania, water/surfactant ratio, process parameters