Photocatalytic degradation of an azo dye by UV irradiation at 254 and 365 nm

The photocatalytic decolorization of aqueous Congo red dye (CR) solution was investigated in TiO2 suspensions irradiated with artificial UV light. Batch photocatalytic tests were carried out by varying the amount of TiO2 and the source of UV radiation. The doses of TiO2 were 0.25, 0.5 and 1.0 g L-1 and the wavelengths of the incident ultraviolet light were predominantly 254 (UV-C) and 365 nm (UV-A). In the presence of TiO2 photocatalyst, UV-A radiation showed higher degradation efficiency of CR than UV-C radiation, with less energy demand (consumption). On the other hand, UV-C radiation without TiO2 photocatalyst was capable of degrading CR, while UV-A radiation alone did not show a potential for CR degradation. CR adsorption on the surface of TiO2 particles is also investigated and described.