Adsorption of Copper (II) from Aqueous Solution by Using Carbonized Peanut Hull: Determination of the Equilibrium, Kinetic and Thermodynamic Parameters

Abstract

In this study, the effect of temperature, pH, initial metal concentration and adsorbent dosage on Cu(II) adsorption onto carbonized peanut hull (PHC) was investigated. Activated carbon was prepared from peanut hull. It was produced by carbonization in carbon diokside atmosphere at 500 °C for 1.0 h. The maximum Cu (II) adsorption capacity was obtained as 168.16 mg/g for 500 mg/L initial Cu (II) at pH = 4.0 and 60 °C. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium. The best interpretation for the experimental data was given by the Freundlich isotherm and the maximum adsorption capacity was obtained. Batch adsorption models, based on the assumption of the pseudo-first and pseudo-second order mechanism, were applied to examine the kinetics of the adsorption. Kinetic data fitted the pseudo-second kinetic order model. Thermodynamic functions, the change of free energy (Go), enthalpy (Ho) and entropy (So) of copper adsorption on PHC were calculated as -23.21 kjmol-1 (at 60 oC), 15.94 kjmol-1 and 117.59 kjmol-1 K-1, respectively, indicating the spontaneous, endothermic and the increased randomness nature of Cu2+ adsorption. The results show that adsorption of Cu (II) on PHC is an.