Continuous ozonation of methylene blue in water

Dyes are the main pollutants in the textile industry effluents. To provide solutions to the environmental problem, a model dye, methylene blue (MB), was removed from aqueous solution by ozonation in a continuous reactor. The effect of liquid circulation on MB removal was investigated and an optimal circulation rate was found under given experimental conditions. Models based on film theory were developed to predict concentration profiles of MB, dissolved ozone and gaseous ozone for the continuous ozonation process. Validation of the models with experimental data indicates that the proposed models can successfully predict the concentration profiles. Evaluation of the models also reveals that the fast kinetic regime assumption was applicable for the mass balance model of MB, however, as evidenced by the presence of dissolved ozone shortly after the reaction started, the intermediate rate assumption better represented the variations of ozone concentration both in liquid phase and in gas phase.