Degradation of pararosaniline (C.I. Basic Red 9 monohydrochloride) dye by ozonation and sonolysis

Pararosaniline (C.I. Basic Red 9) is an important dye used in biological and chemical assays, suspected of being carcinogenic. Thus, the environmental and occupational issues related to it are very important. This study aims at investigating the chemical oxidation of pararosaniline dye by ozonation and sonolytic processes. Experimental results indicate that ozonation of pararosaniline solution is more efficient than ultrasonic irradiation alone or in combination with O3. The detoxification was assessed by determining acute toxicity and mutagenicity of the ozonized dye solutions. Even for short-term ozonation (15 min) any mutagenic effect was verified although longer treatment periods (120 min) are necessary to obtain high toxicity removal. The results obtained indicate that ozonation is a powerful tool for the treatment of the pararosaniline wastes, even when compared to other advanced oxidation processes as photocatalytic and hydrogen peroxide dye degradation. The kinetics of different pararosaniline degradation techniques are also discussed such an understanding is necessary for the design and application of pararosaniline treatment processes.