Aliphatic oxime 3-(hydroxyimino)pentan-2,4-dione as new potential mediator for laccase-catalyzed decolorization of dyes

Abstract

Aliphatic oxime HIPD (3-(hydroxyimino)pentan-2,4-dione) was studied as mediator of laccase (from Trametes versicolor) catalyzed decolorization and detoxication of eight structurally diverse synthetic dyes with typical chromophores including the azo dyes (Acid Red 1, Methyl Orange and Mordant Blue 13), indigo dye (Indigo Carmine), triphenylmethane dyes (Methyl Green, Crystal Violet), anthraquinone dye (Reactive Blue 4) and thiazine dye (Methylene Blue). The results demonstrated the potential and limitations of using 3-(hydroxyimino)pentane-2,4-dione as mediator for enzymatic decolorization of various type dyes. In the presence of a laccase-mediator system almost 100 % biodegradation was observed for Indigo Carmine, Acid Red 1, Methyl Orange and Reactive Blue 4 within 3 h. At the same time, the proposed laccase-mediator system does not decolorize Methylene Blue and exhibits lower efficiency in the degradation of triphenylmethane dyes in comparison with azo dyes. The studied system can be used repeatedly for wastewater treatment. Phytotoxicity tests of the solutions before and after treatment with laccase-mediator system indicated that dyes are converted into low-toxicity metabolites. The proposed system has demonstrated its efficiency in the treatment of artificial wastewater containing high concentrations of azo dyes (0.5 g L−1) and other auxiliaries used in the textile industry. Color reductions of 92 % and 83 % were achieved using laccase-mediator system for Acid Red 1 and Methyl Orange for 7 days in the presence of dye bath components.