Removal of cadmium and mercury ions from aqueous solution by sorption on treated Pinus pinaster bark: kinetics and
G Vázquez1, J González-Alvarez, S Freire
1Department of Chemical Engineering, Faculty of Chemistry, University of Santiago de Compostela, Spain.
Abstract:
Formaldehyde pretreated Pinus pinaster bark was used to sorb Cd2+ and Hg2+ from aqueous solutions. The sorption kinetics showed hyperbolic dependence of the proportion of cation adsorbed on time, and the sorption isotherms were satisfactorily fitted by Freundlich equations, with k and n values showing Hg2+ to be more efficiently sorbed than Cd2+. Except for low cation concentrations, for which sorption was practically total at all initial pH > or = 6, sorption increased in this range, in keeping with a mechanism based on ion exchange with the hydroxyl protons of ring B of the procyanidin units of the tannins in the bark.
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