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

TiO2 and WO3, with and without noble metal cocatalysts, were employed as photocatalytic surfacing agents to inhibit the attachment and growth of Oedogonium, a sessile, filamentous algae. It was demonstrated that coating a cement 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 unprotected cement surface. Adding a 1.0 wt % loading of a noble metal such as Pt or Ir to the photocatalyst enabled an 87% reduction. The extent of inhibition was shown to be related to the amount of near-UV light contained in the irradiation source. The ability of the photocatalysts to inhibit algae correlated well with their ability to photooxidize d-(+)-glucose, building block of numerous biochemical polysaccharides, suggesting a nonspecific mechanism in the breakdown of cellular structures.