Decolorization of the phthalocyanine dye reactive blue 21 by turnip peroxidase and assessment of its oxidation products

Peroxidases can be used in decolorization processes and the treatment of textiles effluents. This study evaluates the potential of the turnip peroxidase enzyme in the decolorization of the phthalocyanine textile dye Reactive Blue 21 (RB21). Some factors such as pH, the amount of H2O2 and the enzyme were evaluated in order to determine the optimum conditions for the enzyme performance. The reaction products formed during the decolorization of the RB21 dye were analyzed by high-performance liquid chromatography–mass spectrometry coupling (LC–ESI/MS). LC–ESI/MS analysis showed that the decolorization of the dye RB21 by turnip peroxidase is due to the breaking up of the chromatogenous system. The tests for toxicity towards lettuce seeds showed an increase of the toxicity after enzymatic treatment of the dye. This study verifies the viability of the use of the turnip peroxidase enzyme in the biodegradation of textile dyes.

Figure optionsDownload as PowerPoint slideHighlights
► RB21 dye was decolorized, due to the breaking up of the chromatogenous system.
► The treatment represents an important step for microbial degradation of dyes.
► The enzyme was used without any purification, which makes the process cheaper.
► The major metabolites formed during the enzymatic degradation were identified.
► A reaction mechanism was proposed.