Enhanced Biodecolorization of Azo Dyes by Using Anthraquinone Immobilized in Polyurethane Foam

The accelerating effect of anthraquinone immobilized in polyurethane foam (PUF) on the biodecolorization of azo dyes was investigated. The results show that, during the biodecolorization, the anthraquinone plays a role of redox mediator, and the optimal conditions for the biodecolorization of amaranth are: 2 g·L-1 glucose, pH 8.0~9.0 and 90 mg·L-1 anthraquinone. Using adsorption method, the anthraquinone was immobilized in 2 polyurethane foam cubes, and the biodecolorization rate of azo dyes in the presence of immobilized anthraquinone is increased 1~3 fold compared with that without anthraquinone. Moreover, the accelerating effect of immobilized anthraquinone is equivalent to that of suspended anthraquinone, while using the immobilized anthraquinone, the anthraquinone loss is much lesser than that of suspended anthraquinone. The reusability of the anthraquinone immobilized in PUF was evaluated with repeated-batch decolorization experiments. After experiments of 10 times repeated using, the decolorization efficiency of the immobilized anthraquinone retains over 90% of its original activity. This indicates that the method of anthraquinone immobilization in polyurethane foam has potential application value for accelerating the anaerobic biodecolorization of azo dyes.