Abstract
Activated carbon prepared from hazelnut shells was used to remove Co(II) from aqueous solution by adsorption. Batch-mode adsorption experiments were carried out varying parameters such as the initial metal ion concentration (13.30–45.55 mg/l), agitation speed (50–200 rpm), pH (2–8), temperature (293–323 K) and particle size (0.80–1.60 mm). The kinetics of the adsorption of Co(II) followed the pseudo-second-order equation, being pH-dependent since the removal rate increased with the pH value of the aqueous solution. The adsorption equilibrium data obeyed the Langmuir isotherm. The adsorption capacity (Q0) calculated from the Langmuir isotherm was 13.88 mg Co(II)/g carbon at 303 K employing a pH value of 6 and a particle size of 1.00–1.20 mm. The thermodynamic parameters evaluated for the carbon revealed that the adsorption of Co(II) was endothermic in nature.