Photocatalytic inhibition of algae growth using TiO2, WO3, and cocatalyst modifications

TiO2 and WO3, with and without noble metal cocatalysts, were employed as ph otocatalytic surfacing agents to inhibit the attachment and growth of Oedog onium, a sessile, filamentous algae. It was demonstrated that coating a cem ent substrate with a dispersion of TiO2 powder held in a 10 wt % hinder and irradiating with a combination of black light and fluorescent lamps could effect a 66% reduction in the growth of algae in comparison to the unprotec ted cement surface. Adding a 1.0 wt % loading of a noble metal such as Pt o r Ir to the photocatalyst enabled an 87% reduction. The extent of inhibitio n was shown to be related to the amount of near-UV light contained in the i rradiation source. The ability of the photocatalysts to inhibit algae corre lated well with their ability to photooxidize d-(+)-glucose, building block of numerous biochemical polysaccharides, suggesting a nonspecific mechanis m in the breakdown of cellular structures.