The application of fluorescence spectroscopy for the investigation of dye degradation by chemical oxidation

Chemical oxidation is a key technique used in dye wastewater treatment via the formation of hydroxyl radicals. To obtain optimaltreatment effects, it is critical to understand the interaction of the molecular structure of the dye with the hydroxyl radical. Weevaluated fluorescence excitation-emission matrix spectroscopy to study the decay of an azo-dye (Procion Red MX-5B) by ahydroxyl radical generated from catalytic Fe (III) on H2O2. Results showed that fluorescence signal reliably indicated thevariations of the chemical groups and components during degradation, and the degradation could be divided into three stages:initial degradation (decolorisation), rapid intermediate degradation, and final degradation. Under control of uncorrected matrixcorrelation, the fluorescence fractions could be fitted successfully by parallel factor model (PARAFAC) model: two fluorescencecomponents in initial degradation including mono substituted benzene and mono substituted naphthalene, three components asmulti substituted benzene in rapid degradation, and no components could be resolved in the final degradation. The results fromthe study demonstrate the utility fluorescence characterization of dye degradation mechanisms and enhance the understanding ofthe degradation mechanisms