| abstract |
A photocatalytic composition containing a substantially non-oxidizable binder, such as silicone, which allows large amounts of photocatalytic particles, such as titanium dioxide or zinc oxide, t o be adhered to a surface. Upon application to a surface, the composition dries or cures to form an adherent, abrasion-resistant, thermostable photocatalytic coating. The binder transmits a substantial proportion of incident ultraviolet light to activate the photocatalytic particles to produce a cleaning effect. The binder, preferably polysilicone, renders the surface hydrophobic. The coated surface can be used to degrade organic contaminants in air or in an aqueous stream, and can act as a biocidal agent under the application of ultraviolet light. When an organic reaction is to be catalyzed under the ultraviolet light, such coated particulate materials can be used as photocatalysts in a fluidized bed reactor, or a packed bed reactor. The photocatalytic composition is used in a photoreactor (14) containing a packed bed (6) packed with glass spheres (2), optionally with a silicone coating only at the points of contact (4), within a conduit (8) which surrounds a source of ultraviolet light (10). Preferably a silicone film (12) is placed between the conduit (8) and the glass spheres. |