Decomposition of dyes by Bilirubin Oxidase

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In order to examine the decolonzation of dyeing effluent by enzyme, aqueous solutions of ten commercial anthraquinone dyes and eight commercial azo dyes were treated with Bilirubin oxidase (BO). Efficient decolorization ofall anthraquinone dyes was confirmed by measuring the visible and UV absorption spectra of the dye solution to which the enzyme was added.An aqueous solution of purified C.I. Acid Blue 40, to ^hich the enzyme wasadded, was shaken at 40 ℃.Aliquots of the solution after the specified time were analyzed by HPLC after removing the enzyme. Thechromatograms showed that the decomposition of dye (C.I. Acid Blue 40) started immediately after the addition of the enzyme. A peak around a retention time of 5.2 min,which can be related to the decomposition complex, increased gradually after the addition of the enzyme and was reached after about 3 h. That peak was nearly maintained even after 24 h, although it gradually decreased. Theabsorption spectrum of the product at that peak was determined by a photodiode array analysis.Efficient decolorization of six azo dyes was confirmed by measureing the visible and tJV absorption spectraof the dye solution in the presence of the enzyme, but that of the two azo dyes, C.I. Direct Black 22 and C.I.Direct Violet 48 was not efficient. Also HPLC was introduced to measure decolorization of dyes. The chromatograms showed that the decomposition of the eight dyes started immediately after the addition of the enzyme. The decolorization ratios calculated from the peak areas in the chromatograms were ca. 100% for first the six dyes and 90% for that last two dyes.