Zinc biosorption on Tectona grandis L.f. leaves biomass:: Equilibrium and kinetic studies

The biosorption of zinc ions from aqueous solution by Tectona grandis L.f. was studied in a batch adsorption system as a function of pH, contact time, zinc ion concentration, adsorbent concentration and adsorbent size. The biosorption capacities and rates of zinc ions onto T grandis L.f. were evaluated. The Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption models were applied to describe the isotherms and isotherm constants. Biosorption isothermal data could be well interpreted by the Langmuir model followed by Temkin model with maximum adsorption capacity of 16.42 mg g(-1) of zinc ion on T grandis L.f. leaves biomass. The kinetic experimental data was properly correlated with the second-order kinetic model. Various thermodynamic parameters such as Delta G degrees, Delta H degrees, and Delta S degrees were calculated indicating that this system was a spontaneous and exothermic process. (c) 2006 Elsevier B.V. All rights reserved.