Decolorization of reactive black 5 by immobilized trametes versicolor

Abstract

Azo dyes released in wastewaters of textile industry are an important factor of environmental pollution. The use of immobilized white rot fungi cells is considered one of the most adequate alternatives to decolorize these effluents. In this work, a 2k factorial design was applied to increase the specific decolorization rate (rd) of Reactive Black 5 (RB5) by Trametes versicolor, using free (FC) and immobilized cells by adsorption in polyurethane foam cubes (IC). The results indicated that IC system was more efficient than FC for decolorization of 200 ppm RB5. Immobilization modified fungal metabolism with a decrease in CO2 production, while laccases increased in presence of RB5. Decolorization process at bioreactor showed that IC (removal of 84% in 24 h) was more efficient than FC (85 % in 144 h). The decolorization of RB5 analyzed using UV-vis spectrophotometry suggested that degradation was the main mechanism for dye removal by IC, whereas in FC both absorption and degradation contributed to color removal.