Photocatalytic Inhibition of Algae Growth Using TiO2, WO3, and Cocatalyst Modifications

TiO 2 and WO 3, 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 TiO 2 powder held in a 10 wt % binder 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.