Chemical Engineering Communications, Vol.198, No.12, 1497-1504, 2011
Thermodynamic and Kinetic Study of Adsorption of Ni(II) Ions on Carbon Anode Dust
In this study the use of carbon anode dust (CAD), which is the solid residue from aluminum production, as a low-cost adsorbent for the removal of Ni(II) ions from wastewater was investigated. A mechanism of adsorption kinetics and thermodynamics was proposed. In order to investigate the adsorption process of nickel ions on CAD three kinetic models were used: Lagergren's pseudo-first-order model, pseudo-second-order model, and the intra-particle diffusion model. Various thermodynamic parameters, such as the energy of activation (E(a)), activation enthalpy (Delta H*), activation entropy (Delta S*), and free energy of activation (Delta G*), were evaluated. Observation of the value of the energy of activation suggests that the process uptake of Ni(II) ions can be described as activated chemisorption. The positive values of enthalpy of activation and free energy of activation, as well as negative values of entropy of activation, mean that the process of removal of Ni(II) ions is endothermic, non-spontaneous, and without structural changes in the solid carbon anode dust particles.