A comparative adsorption/biosorption study of Acid Blue 161:: Effect of temperature on equilibrium and kinetic parameter

In this study dried Trametes versicolor, a white-rot fungus and chitosan, a fungal component derivative were used for the removal of Acid Blue 161 (AB 161) acidic dye from aqueous solution and the results were compared with the outcomes of acid-washed powdered activated carbon (PAC). The influence of suspension pH, temperature, and initial dye concentration on AB 161 dye removal was investigated by conducting a series of batch adsorption experiments. All sorbents exhibited the highest dye uptake capacity at an initial pH value of 3.0. The effect of temperature on dye removal indicated that maximum capacity was obtained at 45 degrees C for each AB 161 dye-sorbent system. Sorption capacity of each sorbent increased with increasing initial dye concentration up to 500 mg l(-1). Among the three sorbents. chitosan was the most effectively sorbent showing a maximum acidic dye uptake of 471.6 mg g(-1) at 45 degrees C. The Freundlich, Langmuir, Redlich-Peterson and Langmuir-Freundlich, the two- and three-parameter adsorption models were used for the mathematical description of the sorption equilibrium and isotherm constants were evaluated depending on sorption temperature. Equilibrium data of AB 161 sorption fitted very well to all models except that the Freundlich model for each acid dye-sorbent system in the concentration and temperature ranges studied. For each sorbent-dye system simple kinetic models were applied to the experimental data to examine the mechanisms of sorption and potential rate-controlling steps such as external mass transfer, intraparticle diffusion and sorption process. The sorption process was found to be controlled by both surface and pore diffusion with surface diffusion at the earlier stages followed by pore diffusion at the later stages. Pseudo-second-order kinetic model described the adsorption kinetics accurately at all concentrations and temperatures studied. The thermodynamic analysis indicated that the sorption process was endothermic and the sorption of dye on each sorbent might be chemical in nature. (c) 2007 Elsevier B.V. All rights reserved.