Photovalorisation of pentafluorobenzoic acid with platinum doped TiO2

Pt-doped TiO2 has been prepared and characterized by various surface analytical methods such as BET surface area, scanning electron micrographs (SEM). X-ray diffraction (XRD), energy dispersive X-ray micro analysis (EDX) and diffuse reflectance spectroscopy (DRS). Photodefluoridation of pentafluorobenzoic acid (PFBA) to fluoride ions has been carried out using TiO2 and Platinum doped TiO2 with UV-C (200-300 nm) light. The defluoridation was monitored by the ionometer with fluoride ion selective electrode. Photodeposition of 1.5% Platinum on the surface of TiO2 enhances its photoactivity in pentafluorobenzoic acid defluoridation. In order to optimize the working conditions, effects of pH and initial PFBA concentration were analyzed. Addition of inorganic oxidizing species KIO4. H2O2, (NH4)S2O8 and KBrO3 strongly influenced the photocatalytic defluoridation of PFBA. The significant enhancement in the Pt-TiO2 photoactivity under UV irradiation can be ascribed to the platinum deposits, acting as electron traps on the Pt-TiO2 surface. The fluoride ions formed during photodefluoridation can be used for the production of CaF2. (C) 2009 Elsevier B.V. All rights reserved.