Synthesis of TiO2 Nanoparticles in Reverse Microemulsion and Microstructural Changes of Particles During Calcination

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 28 nm in the system of cyclohexane with surfactant when the molar ratio of water to surfactant was 2. 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. The titania nanopowders were characterized by means of X-ray diffraction and SEM، TEM، FT-IR، and DTA. The titania calcined at 500 ºC shows the highest activity on the photocatalytic decomposition of methylene blue.