Photocatalytic Activity of TiO2 Powders Synthesized by Supercritical Gas Antisolvent Method

Synthesis of nanocrystalline, spherical, and anatase type TiO2 photocatalyst were performed by supercritical gas antisolvent process in the range of 50-150 degrees C and 100-150 bar. As-prepared samples were calcined at 500 degrees C and characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller method, differential thermal analysis/thermal gravimetry. In X-ray diffraction analysis, the anatase crystalline phase of titanium dioxide has been detected. The mean crystalline size of powders is about 13 nm. The photoactivity test of the powders was evaluated by the photodegradation of aqueous RR 180 (reactive red 180) solution under UV light. While the photocatalytic performance of TiO2 powders (Brunauer-Emmett-Teller surface area of 69.2 m(2)/g) produced at 150 bar and 150 degrees C was found to be 98%, only 25% degradation was observed with powder produced at 150 bar and 100 degrees C. Results showed that the powder properties and photocatalytic activity can be tuned by controlling the supercritical conditions such as temperature and pressure.