The Influence of FeCl sub(3) on the Photocatalytic Degradation of Dissolved Azo Dyes in Aqueous TiO sub(2) Suspensions

Selected azo dyes, the characteristics of which are tabulated, were subjected in aqueous solution to photodegradation in the presence of titanium dioxide, and the influence of FeCl sub(3) on decolorization was studied. The addition of FeCl sub(3) caused the initiation of decolorization before illumination of the anionic dyes, which resulted in a significant intensification of the process during illumination. The presence of FeCl sub(3) caused a decrease in the level of decolorization of the cationic dye solutions, however. When Acid Orange 7 was used, decolorization occurred more efficiently at higher FeCl sub(3) concentrations, which reduced the required amount of TiO sub(2), but increasing concentrations of Acid Orange 7 above an optimal level reduced the level of decolorization.