HYDROXYL RADICAL-MEDIATED DEGRADATION OF AZO DYES - EVIDENCE FOR BENZENE GENERATION

This study demonstrates that Fe3+−H2O2 treatment degrades a substantial portion of azo dyes to water-soluble products and CO2. There is definitive evidence for the generation of benzene when azo dyes with a phenylazo substitution are degraded with Fe3+−H2O2. Benzene is a priority pollutant; it causes leukemia in humans and reproductive impairment in fish (36). Several watersoluble commercial azo dyes such as Naphthol Blue Black, Azogeranine, Chromotrope 2R, and Direct Orange 2G have a phenylazo substitution as part of the dye structure and are likely to generate benzene when degraded with ·OH. Textile industry effluent usually contains a mixture of dyes. This study cautions that, in such a situation, the structure and concentration of individual azo dyes should be known before the effluent is treated using a process which relies on the hydroxyl radical chemistry. © 1994, American Chemical Society. All rights reserved.