PHOTODEGRADATION OF CHLOROFORM AND UREA USING AG-LOADED TITANIUM DIODE AS CATALYST

The photodegradation of chloroform and of urea in aqueous solutions was investigated under near-u.v. and visible radiation using the anatase form of TiO2 as catalyst. It has been shown that the catalytic activity of the TiO2 can be increased by loading silver, in a proportion of 1% (w/w), onto the oxide surface. In a solution containing 200 mg l-1 of chloroform, the photodegradation achieved using the Ag-loaded oxide was 44% compared to the 35% obtained using the pure (unloaded) oxide. This photoactivity was further enhanced in a solution containing 25 mg l-1 of chloroform. Upon reuse, a decrease in the photocatalytic activity was observed in both oxides, but to a lesser extent in the Ag-loaded TiO2. An increase in the photocatalytic activity of the silver-loaded oxide was also noted in the degradation of a 100 mg l-1 aqueous solution of urea. After 12 min of irradiation, the Ag-loaded oxide destroyed 83% of this compound, compared to a 16% efficiency obtained for the pure form of anatase. After 6 h of irradiation, 0.5 mg l-1 of silver ions were detected in the Ag-loaded TiO2 suspension.