Oxidative degradation of Remazol Turquoise Blue G 133 by soybean peroxidase

Reactive dyes are widely employed in textile industries and their removal from wastewaters is a relevant environmental problem. In addition to chemical and physical methods, several bioremediation approaches, involving intactmicro-organisms or isolated enzymes, have been proposed to decolorize dye solutions. In this paper, we report the complete and fast decolourization of a Cu(II)-phthalocyanine based reactive dye (Remazol Turquoise Blue G 133) by means of the soybean peroxidase/H2O2 system. The oxidative degradation of the dye in aqueous solution at 25 °C was studied as function of pH, revealing a quantitative decolourization yield at acidic pH values with a maximum of activity at pH 3.3. The reaction products were identified and characterized by HPLC–diode array detector (DAD)–mass spectrometry (MS), ionic chromatography and EPR techniques. This analysis showed that the enzyme catalyses the breaking of the phthalocyanine ring producing sulfophthalimide as the main degradation product, and the release of stoichiometric amount of ammonium and Cu(II) ions.