Photocatalytic reduction of divalent zinc and cadmium ions in aqueous TiO2suspensions: an interfacial induced adsorption-reduction pathway mediated by formate ions

A new pathway is described for the photocatalytic reduction of metal ions i n organic-loaded aqueous TiO2 suspensions. Thus, formate ions act as interf acial anchors to initially sequester Zn(II) and Cd(II) ions onto the TiO2 p article surfaces. Subsequent UV illumination of the suspensions results in the facile photoreduction of these metal ions. In the absence of formate, t he metal ions show little proclivity either to adsorb on the TiO2 particle surfaces or to undergo photoreduction. (C) 2000 Elsevier Science S.A. All r ights reserved.