Decolorization of the azo dye reactive black 5 using laccase mediator system

Abstract

Laccase mediator system (LMS) has been widely used in various fields. In this study, we tested the capacity of LMS in the decolorization of a recalcitrant azo dye Reactive Black 5 (RB5). Both acetosyringone and syringaldehyde demonstrated high mediating ability for RB5 decolorization and acetosyringone was proved to be the most efficient mediator. The decolorization process was not significantly affected at various temperature and pH, and the laccase mediator system still maintained high efficiency when the dye concentration increased. The optimized conditions for dye decolorization were 160 mg/L of RB5, 0.5 U/ml of laccase and 0.1 mmol/L of mediator at 40°C and pH 7.0. More than 92% of RB5 was decolorized with acetosyringone as mediator in only 30 min. The results show an enormous potential of this laccase mediator system in the treatment of azo dye effluents.

Key words: Azo dye, reactive black 5, mediator, laccase, decolorization.