Resumen
The study presents the results regarding the photocatalytic behavior of some water-based styrene-acrylic coatings containing TiO2 nanoparticles sensitized with metal-phthalocyanine tetracarboxylic acids. Coating materials have been studied in terms of color characteristics, photocatalytic behavior, and resistance to self-degradation depending on the structure of phthalocyanine sensitizers. Coatings that were exposed to Xenon light showed degradation of the organic sensitizer rather than of the binder. Photocatalytic tests using methylene blue as a standard contaminant indicated that the coating containing TiO2 nanoparticles sensitized with Fe(III) phthalocyanine tetracarboxylic acids showed the highest efficiency both in ultraviolet or visible light. In this case, the UV light induced a photodegradation rate that was greatly increased of about fifty times comparatively with that induced by LED light and was determined by two different mechanisms, but side reactions like methylene blue and sensitizer self destruction are possible to occur simultaneously. Photocatalytic materials of this type are suitable to be used as decorative coatings especially for indoor applications.