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Photodegradation of Dye Acid Orange 67 by Titanium Dioxide in the Presence of Visible Light and UV Light

Rachita Mehta and Menka Surana

The photocatalytic degradation of azo dyes containing different functionalities has been reviewed using TiO2 as photocatalyst in aqueous solution under solar and UV irradiation. The mechanism of the photodegradation depends on the radiation used. Kinetic analyses indicate that the photodegradation rates of azo dyes can usually be approximated as pseudo-first-order kinetics for both degradation mechanisms, according to the Langmuir–Hinshelwood model. The degradation of dyes depends on several parameters such as pH, catalyst concentration, and substrate concentration. The application of novel treatment methods encompasses investigations of advanced oxidation processes (AOP’s), which are characterized by production of the hydroxyl radical (OH) as a primary oxidant. In this work, we investigated the photocatalytic oxidative degradation and discoloration of acid dye and dye intermediates using light (UV/visible)/semiconductor catalyst by optimizing the operational parameters to ensure the rapid and complete transformation of the toxic organic compounds to benign chemicals. The results showed that efficiency of dye degradation is much better when light source is UV in comparison to Visible.