Biosorption of phenol on dried activated sludge: Effect of temperature

Abstract

In this study, the effectiveness of dried activated sludge in removing phenol from aqueous solutions was examined by biosorption as a function of temperature, pH, and initial phenol concentration. Batch kinetic studies showed that an equilibrium time of 60 min was needed for the biosorption. The maximum phenol biosorption capacity was obtained as 42.7 mg g(-1)at the temperature of 40 degrees C at pH = 8.0. The Freundlich and Langmuir adsorption models were used for the mathematical description of the biosorption equilibrium and it was reported that experimental data fitted very well to the Freundlich model. Adsorption rate data were analyzed using the pseudo-first order kinetic model of Lagergren and the pseudo-second order model to determine adsorption rate constants at 10, 25, and 40 degrees C. It was reported that, the pseudo-second order kinetic model provided the best correlation of the experimental data rather than the pseudo-first order model. The thermodynamic parameters such as, Gibbs free energy changes (Delta G degrees), enthalpy change (Delta H degrees) and entropy change (Delta S degrees) were determined. The results show that biosorption of phenol on dried activated sludge is an endothermic and spontaneous in nature.