Adsorption Kinetics, Isotherm and Thermodynamic Study of Hg(II) Ions on Hazelnut-Shell-Derived Activated Carbon

Abstract

In this study, the adsorption capacity of Hg(II) ions from aqueous solutions was examined using physically prepared HS-AC, an economical and natural biosorbent. The effects of various parameters, including solution pH, adsorbent dosage, initial metal ion concentration, contact time, and temperature, on Hg(II) adsorption were systematically investigated. The kinetic data obtained for the process were well described by the pseudo-second-order model, whereas the equilibrium data were consistent with both the Langmuir and Freundlich isotherms. Notably, the equilibrium data exhibited a higher degree of conformity with the Freundlich isotherm (R-2 = 0.9965) compared to other isotherm models. Thermodynamic parameters, including Gibbs free energy change, enthalpy change, and entropy change, were calculated for the adsorption process, and the results indicated that the adsorption occurred spontaneously and proceeded with an exothermic nature.