Preparation of activated carbon from Pterocarya fraxinifolia and Isotherms and thermodynamics evaluation for Pb (II) sorption

Low-cost activated carbon was prepared from Pterocarya fraxinifolia. To determine the adsorption process the effects of various operating parameters, initial concentration of metal ions (50–200 mg/L) and temperature (298–328 K) were investigated in a batch adsorption technique. Equilibrium data were analyzed by the Langmuir and Freundlich isotherm model. Langmuir and Freundlich isotherms provided the best fit to the equilibrium data and maximum adsorption capacity of 370.370 mg/g at 298 K. The thermodynamic parameters, such as Gibb’s free energy change (ΔG), standard enthalpy changes (ΔH) and standard entropy change (ΔS) was evaluated. The value of ΔG was found negative for the adsorption of Pb (II) which confirmed the feasibility and spontaneity of the adsorption process.