Degradation of rhodamine B/phenol mixtures in water by sun-like excitation of a Bi2 WO6-TiO2 photocatalyst.

Bi2 WO6 and Bi2 WO6-TiO2 (5% molar Ti) nano-heterostructures were synthesized by a hydrothermal method. The properties of the synthesized catalysts were characterized, having high photoactivity for Rhodamine B degradation under sun-like illumination, explained by a synergetic mechanism previously proposed through UV and visible induced processes, in which the photosensitization effect of Rhodamine B is considered. We now report that using Phenol, a molecule which does not lead the photosensitization process, the photoactivity decreased considerably, thus emphasizing how important is the model molecule selected as degradation substrate for evaluating the photoactivity. The photocatalytic properties of the synthesized catalysts have been evaluated by exposing a mixture of Rhodamine B and Phenol in water, to different illumination conditions. It can be confirmed that the photoinduced mechanism via the photosensitization of Rhodamine B is a key factor responsible for the increase on the photocatalytic activity showed by the Bi2 WO6-TiO2 compound and that the degradation mechanism of Rhodamine B is not changed by the simultaneous presence of other transparent substrate as Phenol.