Pathways of Solar Light-Induced Photocatalytic Degradation of Azo Dyes in Aqueous TiO sub(2) Suspensions

Tests utilized a light source capable of simulating solar illumination to analyze the photocatalytic degradation of aqueous solutions of Acid Orange 7 in TiO sub(2) suspensions. Techniques used to monitor the degradation of the dye and the formation of intermediates and final products following the photoreaction process are discussed. These parameters were evaluated as functions of the time of irradiation, both in solution and on the photocatalyst surface. Evidence from the study showed that the dye adsorbs onto TiO sub(2) and experiences a number of oxidation steps. These processes result in decolorization and production of a variety of intermediates, primarily aromatic and aliphatic acids. A mechanism for the photodegradation of Acid Orange 7 is proposed.