Effects of some water-quality and operating parameters on the decolorization of reactive dye solutions by ozone

The ozonation of reactive dye solutions has been investigated. Results of studies on ozone mass transfer indicated that the volumetric mass transfer coefficient of ozone increased with the following water-quality and operating parameters: pH, initial dye concentration, applied ozone dose, and temperature. A model was developed to predict the volumetric mass transfer coefficient of ozone from the above parameters. The results of kinetic studies showed that ozonation of the aqueous reactive dye was a pseudo-first-order reaction with respect to the dye. The apparent rate constant increased with the pH, applied ozone dose and temperature, however, it declined logarithmically with the initial dye concentration. Meanwhile, Ozonation enhanced the biodegradability and reduced the COD of the reactive dye wastewater effectively.