Aspects on the sorption behavior lead from aqueous solutions onto carbonized apricot stone

The kinetics and thermodynamic parameters of Pb21 adsorption onto apricot stone from aqueous solutions were evaluated. The external mass transfer coefficient was determined at different temperatures and the apparent activation energy for the adsorption process was found to have the value 5.7 kd.mol1. The enthalpy change of the sorption process had positive value implying its endothermic nature . The change in free energy was small over the 30 - 50 degree C temperature range, and its negative values suggests a spontaneous sorption process with high preference of Pb21 for apricot stone. The equilibrium data fit freundlish isotherm model and the isotherm constants were determined at different temperatures