Kinetics and thermodynamics of reactive blue 222 biosorption by Saccharomyces cerevisiae

Biosorption of Reactive Blue 222 ions by the yeast Saccharomyces cerevisiae has been investigated as a function of medium conditions. For Reactive Blue 222, optimum medium conditions were determined as pH 2.0, 30 °C temperature, 200 ppm initial Reactive Blue 222 concentration and 2.0 g/L biomass concentration. At these conditions, maximum Reactive Blue 222 uptake was 93.84 mg/g. Ethanol, methanol and heat treatment enhanced the Reactive Blue 222 biosorption capacity. The cells at lag phase of growth curve of S. cerevisiae have a higher biosorptive capacity for dye ions than that of stationary phase. The early stages of the logarithmic phase of yeast are provided with a higher dye removal. It is seen that dye removal from biosorbent is difficult and efficiency of desorption of dye ions from Reactive Blue 222 loaded biosorbent is low. The salt, which is probably found in textile industry waste water, has negative effects on biosorption of Reactive Blue 222.Biosorption of Reactive Blue 222 ions by S. cerevisiae was explained well with Langmuir model and biosorption kinetics of these dye ions follows pseudo-second order rate model. Activation energies for dye ions were determined as 12.9 kcal.mol-1. Biosorption heat for Reactive Blue 222 ions were calculated as, 22.25 kcal.mol-1 which indicates that biosorption is endothermic and chemical adsorption occurs. This explains also that the low desorption efficiency.