Mechanism and kinetic model for the decolorization of the azo dye Reactive Black 5 by hydrogen peroxide and UV radiation

• Published in: Chemosphere (Oxford) 2003-08, Vol.52 (6), p.1069-1077
• Main Authors: Mohey El-Dein, A., Libra, J.A., Wiesmann, U.
• Format: Article
• Language: English
• Subjects: Advanced oxidation process; Applied sciences; Azo Compounds - chemistry; Coloring Agents - chemistry; decolorization; Exact sciences and technology; H 2O 2; Hydrogen Peroxide - chemistry; Industrial wastewaters; Kinetic model; Kinetics; Models, Chemical; Naphthalenesulfonates - chemistry; Photochemistry; Pollution; Reactive azo dye; Reactive Black 5; Reference Values; Ultraviolet Rays; UV intensity; Wastewaters; Water Purification - methods; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(03)00226-1

A kinetic model for the decolorization of C.I. Reactive Black 5 by the combination of hydrogen peroxide and UV radiation was developed based on experimental results and known chemical and photochemical reactions. The observed kinetic reaction coefficient was determined and correlated as a function of hydrogen peroxide concentration and UV intensity. The validity of the rate expression was tested experimentally in a parameterization study. The decolorization rate follows pseudo-first order kinetics with respect to dye concentration. The rate increases linearly with UV intensity and nonlinearly with increasing hydrogen peroxide concentration, going from a linear relationship at low H 2O 2 concentrations to a maximum as hydrogen peroxide concentration continues to increase. The decolorization rate expression derived from the proposed reaction mechanism was reconciled with that used for correlating the experimental data.