Ozonation of Azo Dye Acid Black 1 under the Suppression Effect by Chloride Ion

The aim of this study is to determine the kinetics of the Acid Black 1 dye by oxidizing action of ozone and to evaluate the influence of chloride ion contamination on the dye degradation. Pseudo-first order kinetics was observed for both decolorization (620 nm) and aromatic structure (321 nm) degradations. A complete color removal was verified in 25 min ([dye](0) = 1.8 x 10(-5) mol L-1), while aromatic structures degraded at slower rates. The presence of chloride ion, the principal impurity of the solid dye reagents, influences significantly the ozonation rate (-42%), even at low chloride concentration (5.6 x 10(-4) mol L-1). The most probable mechanism for the chloride suppression effect involves a direct reaction between O-3 and Cl- generating HOCl, among other by-products. In despite of that, ozonation could be a competitive degradation process for this dye.