New insights into mechanisms of dye degradation by one-electron oxidation processes

The one-electron transfer oxidation of a series of arylazonaphthol dyes has been investigated by pulse radiolysis techniques. These techniques have been used to measure dye redox potentials and to study the initial phases of dye degradation by detecting and following the fate of reaction intermediates. It is shown that bimolecular reaction of dye radicals generated by one-electron oxidation of the common anion represents a novel and generic route for bleaching of azo dyes. Dye degradation by enzymes such as peroxidase or laccase that also generate dye radicals is likely to proceed by the same route.