Photocatalytic nitrate reduction over metal modified TiO2

Photocatalytic removal of nitrates from water was examined using Cu, Fe and Ag containing titania based materials, and using a range of hole scavengers. In the presence of formic acid, complete nitrate removal was possible with all catalysts. All catalysts presented high activities and overall selectivites, with Ag containing catalysts in particular reaching residual levels of nitrite and ammonium below the EU guideline levels for drinking water. Some titania samples exhibited an induction period prior to the onset of nitrate removal and the size of the titania particles was found to influence the photocatalytic performance. An extended induction period for iron containing catalysts, which was absent during second and subsequent reaction tests, was attributed to a leaching of part of the Fe from the catalysts to reveal active sites of the titania support.