Ozonation of C.I. Reactive Black 5 and Indigo

The ozone transfer for the ozonation of the azo dye Reactive Black 5 (RB5) and indigo was investigated using a bubble column at semi-batch conditions. The results were analyzed by applying film theory and surface renewal theory. The ozonation of both dyes was so fast that an instantaneous reaction directly at the bubble surface can be assumed. The ozone balance in the gas phase was used to determine the volumetric mass transfer coefficient k_La and the enhancement factor E. Besides the measured concentrations, temperature and pressure only the Henry coefficient was required for the determination of k_La and E. By varying the ozone inlet and the dye concentration the reaction regime was identified. The Hatta number Ha which requires uncertain parameters did not have to be determined.