Removal of lead(II) by adsorption onto Viscum album L.:: Effect of temperature and equilibrium isotherm analyses

The removal efficiency of Viscum album L. from lead containing aqueous solutions was investigated. The effect of adsorbent mass, pH of solution, initial Pb(II) concentration and temperature was investigated using a batch adsorption technique. The optimum pH for Pb(II) adsorption was found as 3.0 for Viscum album L. Results were analyzed by the Langmuir, Freundlich, Temkin and Harkins-Jura, equation using linearized correlation coefficient at different temperature. The characteristic parameters for each isotherm have been determined. The Langmuir model agrees very well with experimental data than the other models. According to Langmuir isoterm, the monolayer saturation capacity (Q(o)) is 769.23 mg/g at 25 degrees C. Models and the isotherm constant were evaluated depending on temperature. Thermodynamic parameters such as Delta H degrees, Delta S degrees and Delta G degrees were calculated. The adsorption process was found to be endothermic and spontaneous. The experimental data were analyzed using the first- and the second-order kinetic models. The rate constants of adsorption for both kinetics models have been calculated. The second-order model provides the best correlation of the data. (c) 2006 Elsevier B.V. All rights reserved.