Comparative studies on the deactivation and regeneration of TiO2 nanoparticles in three photocatalytic oxidation systems:: C7H16, SO2, and C7H16-SO2

Three photocatalytic oxidation (PCO) systems: C7H16-O-2, SO2-O-2 and C7H16-SO2-O-2 were carried out with the aid of UV-illuminated TiO2 nanoparticles at room temperature in a batch reactor. In C7H16-O-2-TiO2 system, no catalyst deactivation was observed, while for SO2-O-2-TiO2 and C7H16-SO2O2-TiO2 systems, the photocatalytic activity of used TiO2 powder showed decreasing and eventually no activity after used consecutively. The reaction products such as sulfur trioxide or sulfuric acid adsorbed onto the surface of TiO2 catalyst were poisoning species. Photocatalytic activity of the deactivated TiO2 powder could be regenerated by sonicating treatment with water and methanol for the two systems, respectively. (C) 2002 Elsevier Science (USA).