Durability of Ag-TiO2Photocatalysts Assessed for the Degradation of Dichloroacetic Acid

摘要

The stability of Ag-TiO2photocatalysts 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 ofH+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-TiO2photocatalysts as different with Ag loadings . All the Ag-TiO2and bareTiO2photocatalysts 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 byCl−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-P25TiO2photocatalysts 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-TiO2photocatalysts is shown to be of significant importance for the observed changes in the photocatalytic activity of the Ag-TiO2particles.