Equilibrium and kinetic modelling of biosorption of Remazol Black B by Rhizopus arrhizus in a batch system:: effect of temperature

The biosorption of Remazol Black B, a vinyl sulphone type reactive dye, from aqueous solutions on dried Rhizopus arrhizus was studied in a batch system with respect to the temperature, initial pH and initial dye concentration. The fungal biomass exhibited the highest dye uptake capacity at 35 degreesC, at the initial pH value of 2.0 and at the initial dye concentration of 800 mg l(-1). The Freundlich and Langmuir adsorption models were used for the mathematical description of the biosorption equilibrium and isotherm constants were evaluated at different temperatures. Equilibrium data fitted very well to the Freundlich model in the studied concentration (20-800 mg l(-1)) and temperature (25-55 degreesC) ranges. The pseudo first- and second-order kinetic models were also applied to the experimental data assuming that the external mas transfer limitations in the system can be neglected and biosorption is chemisorption controlled. The results indicated that the dye uptake process followed the pseudo second-order rate expression and adsorption rate constants increased with increasing temperature up to 35 degreesC and decreased with increasing concentration. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.