Abstract
In order to examine the decolorization of dyeing effluent by an enzyme, aqueous solutions of eight commercial azo dyes (C.I. Direct Green 59, C.I. Direct Blue 15, C.I. Reactive Black 5, C.I. Direct Blue 6, C.I. Direct Black 51, C.I. Direct Red 2, C.I. Direct Violet 48, and C. I. Direct Black 22) were treated with bilirubin oxidase (BO). Efficient decolorization of the former six dyes was confirmed by measuring the visible and UV absorption spectra of the dye solution in the presence of the enzyme, but that of the latter two 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.
