Acid blue 92 photocatalytic degradation in the presence of scavengers by two types photocatalyst

Abstract

Two types of nanosized photocatalyst, TiO₂ P-25 and ap/Ag/AgBr/TiO₂, were used for decolorization of Acid Blue 92 (AB92) in dark, visible light (V-L), and UV media. Under UV and V-L, the effect of three possible photodegradation processes of AB92 including photocatalytic degradation, self-photosensitization, and direct photolysis were studied. Results showed that in UV/photocatalysts, photocatalytic degradation is the major process for photodecolorization. However, in the presence of TiO₂, self-photosensitization has the major role under V-L. Because of the presence of AgBr as photoactive center in ap/Ag/AgBr/TiO₂, the main process is the photocatalytic degradation in V-L. By using isopropanol and catalase as ^•OH and H₂O₂ scavenger, the results showed that in ap/Ag/AgBr/TiO₂, ^•OH and hole act as AB92 oxidizer, respectively, while in TiO₂, ^•OH, hole, and also H₂O₂ play that role. Meanwhile, AB92 showed a different regular behavior with KI in photodegradation processes. This phenomena is assisted by the formation of I₂ in photocatalytic process. By direct oxidation, I₂ increases the reaction rate and shifts the maximum wavelength absorption of AB92. © 2011 American Institute of Chemical Engineers Environ Prog, 2011