International Journal of Photoenergy 
Volume 2008 (2008), Article ID 280513, 11 pages
doi:10.1155/2008/280513
Research Article

Durability of Ag-TiO2 Photocatalysts Assessed for the Degradation of Dichloroacetic Acid

Víctor M. Menéndez-Flores,1 Donia Friedmann,2 and Detlef W. Bahnemann1

 1Institut für Technische Chemie, Leibniz Universität Hannover, Callinstraße 3, D-30167 Hannover, Germany
2Interdisciplinary Nanoscience Center, University of Aarhus, Building 520, 8000 Aarhus C, Denmark
Received 31 March 2008; Revised 21 July 2008; Accepted 13 August 2008

Recommended by Russell Howe

Abstract

The stability of Ag-TiO2 photocatalysts was examined for the photocatalytic degradation of dichloroacetic acid (DCA) as a function of the recycling times. The photocatalytic activity was investigated by measuring the rate of H+ ions released during the photodegradation of DCA and confirmed by measuring the total organic carbon removal. The photodegradation reactions were studied at pH 3 and pH 10 for a series of Ag-TiO2 photocatalysts as different with Ag loadings . All the Ag-TiO2 and bare TiO2 photocatalysts showed a decrease in photocatalytic activity on recycling for the DCA photodegradation reaction. The decrease in activity can be attributed to poisoning of active sites by Cl− anions formed during the photocatalytic DCA degradation. The photocatalytic activity was, however, easily recovered by a simple washing technique. The reversibility of the poisoning is taken as evidence to support the idea that the recycling of Ag-P25 TiO2 photocatalysts does not have a permanent negative effect on their photocatalytic performance for the degradation of DCA. The choice of the preparation procedure for the Ag-TiO2 photocatalysts is shown to be of significant importance for the observed changes in the photocatalytic activity of the Ag-TiO2 particles.