Decolorization of azo and anthraquinone dyes in hydrophobic organic media using microperoxidase-11 entrapped in reversed micelles

Abstract

Microperoxidase-11 (MP-11), which is a heme-containing undecapeptide derived from horse heart cytochrome c, was utilized as a peroxidative catalyst in the system of bis(2-ethylhexyl)sulphosuccinate sodium salt (AOT)-reversed micelles to oxidatively decolorize water-insoluble dyes in isooctane. MP-11 entrapped in the reversed micelles exhibited a peroxidative activity in the presence of H 2O 2, effectively catalyzing the oxidative decolorization of an azo dye Solvent Yellow 7 and an anthraquinone dye Solvent Blue 11 in the hydrophobic organic solvent. H 2O 2-derived heme bleaching was successfully suppressed by replacing H 2O 2 with an organic hydroperoxide, tert-butyl hydroperoxide ( t-BuOOH), thus sustaining a stable decolorization activity in the system. To optimize the reversed micellar system, the effect of the pH and the molar ratio of H 2O/AOT hydration degree (Wo) was examined, indicating that MP-11 exhibited a maximal decolorization activity at pH 8–10 with the Wo value of 20.