The photocatalytic degradation of the mono azo dye Reactive Yellow 23 was investigated in aqueous solutions containing TiO2 suspension as photocatalyst . Results showed that adsorption played an important role in the photocatalytic degradation rate. By comparing the disappearance of RY23 followed by HPLC-DAD (high performance liquid chromatography-diode array detector) and the bleaching of the solution followed by UV-Vis spectrometry (wavelength of analysis = 430 nm), two different kinetics were found proving that some of the intermediate products were still colored. This was confirmed using HPLC-DAD and HPLC-MS (high performance liquid chromatography- mass spectrometry) analysis. The degradation of RY23 should lead to the formation of carboxylic acids (formic, acetic and oxalic). The decrease of Total Organic Carbon (TOC) in dye solution was measured to monitor the dye mineralization process. Major identified intermediates are hydroxylated derivatives. The Langmuir kinetic treatment was chosen because it has already been successfully used to describe solid-liquid reactions of photocatalytic degradation.
I. Bouzaida, C. Ferronato, J.M. Chovelon, M.E.B. Rammah, J.M. Herrmann