Optimisation of reactive dye degradation by laccase using Box-Behnken design

A three-level Box-Behnken factorial design with three factors and the Response Surface Methodology were used to optimise the colour removal of the reactive textile dye, Colour Index (C.I.) reactive red 180, by commercial laccase. A mathematical model was developed to study the effect of temperature, pH, enzyme concentration and their interactions on the decolourisation. Enzyme concentration and pH as well as their interaction were the principal factors that affected the decolourisation. The dye degradation was independent of temperature. The model estimated that the highest decolourisation (> 92%) was obtained for 27 degrees C, pH 7.5 and 85 U l(-1). This predicted value was experimentally validated, obtaining dye colour removal (540 nm) of 93 +/- 1.5%.