Dyes, which represent a large and important group of synthetic chemicals, are also
important water pollutants, present in the effluents of the textile, leather, paper,
synthetics, cosmetics, and dye manufacturing industries. The release of these
compounds into the environment is undesirable, not only for aesthetic reasons, but also
because many azo dyes and their breakdown products are toxic and/or mutagenic for
life forms. Some conventional technologies (precipitation, adsorptive techniques, ion
exchange, coagulation, flocculation, UV/ozone treatment, electrochemical reduction,
photocatalytic degradation, biological treatment) may be efficient in the removal of
dyes, but their operational costs are very high