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



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