Ecology, Environment and Conservation Paper

DETERMINATION OF EQUILIBRIUM, KINETICS AND THERMODYNAMICS OF BIOSORPTION OF NICKEL (II) AND CADMIUM (II) IONS BY SLUDGE

Ahmad Ashfaq

Abstract

The equilibrium, kinetics and thermodynamics have been studied for the removal of Ni(II) and Cd(II) ions from dilute aqueous solutions onto sewage sludge, in batch mode. The Freundlich and Langmuir sorption models were used for the mathematical description of biosorption equilibrium and isotherm constants were evaluated. The maximum biosrption capacity for Ni(II) and Cd(II) ions were obtained as 29.74 mg and 46.58 mg per gram of the biosorbent applied. The pseudo-second-order model correlated with the experimental data better than the pseudo-first-order model. At different temperatures (15oC to 40oC), the thermodynamic properties were determined and biosorption process of both heavy metal ions considered was found to be endothermic and spontaneous in nature.