Bioseparation of Pb(II) and Cd(II) from aqueous solution using cork waste biomass. Modeling and optimization of the parameters of the biosorption step

In this work the ability of cork wastes to remove Cd(II) and Pb(II) from aqueous solutions has been studied. The kinetics of the biosorption system, the influence of the aqueous pH and the initial metal concentration on the metal uptake were investigated, showing a pH dependent profile. The maximum sorption for both metals was found at pH 5, independently that if the metals were in individual solutions or mixed. When a solution of the mixed metals were studied, a reduction in the Cd(II) uptake was observed showing a clear competition between the metals which was corroborated by the P-factor approach, behavior probably due to a lower attraction of this metal towards the corresponding active groups of the cork. Finally, the cork has been evaluated by FTIR and SEM in order to determine if the biosorption process modifies its chemical structure and morphology, respectively. Cork has been proved to be an efficient biomaterial useful for heavy metal separation purposes that is not altered by the process. (C) 2011 Elsevier B.V. All rights reserved.