Biphase TiO2 Microspheres with Enhanced Photocatalytic Activity

TiO2 microspheres (TMS) with perfect spherical morphology were synthesized by spray drying of a hydrothermally cured aqueous suspension of TiO2 nanoparticles. TiO2 powders (TP) obtained by drying the nanoparticle suspension were studied simultaneously to determine which was the most efficient photocatalyst. SEM images and laser granulometry on TMS show spherical morphology with the diameter ranging from 2 to 10 mu m. TMS had high specific surface area after annealing as seen from BET analyses. XRD analyses show that TMS consist of anatase and rutile crystalline phases where the rutile fraction increases with annealing temperature and above 500 degrees C rutile dominates anatase. Raman spectroscopy shows several Raman bands from anatase and rutile phases and supports the XRD results of phase transformation with increasing annealing temperature. Photodegradation of organic pollutants in aqueous solution under UV light irradiation establishes the higher photocatalytic activity of TMS with respect to TP. The highest efficiency was found on the 400 degrees C annealed TMS.