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ABSTRACT
Equilibria and mechanisms involved in the adsorption process of metal ions (Cr3+, Cu2+, Ni2+, Pb2+ and Zn2+) from aqueous solutions using coniferous barks as biosorbent substrate were investigated. Crude barks were used in this study since previous experiments showed a decreasing uptake for chemically treated barks in the considered granulometry. In our experimental conditions, the maximum binding capacity of barks followed the decreasing order Cr3+>Cu2+>Pb2+>Ni2+>Zn2+ whereas their general binding affinity decreased as: Pb2+>Cr3+> Ni2+>Zn2+>Cu2+. Adsorption isotherms at the optimal physico-chemical conditions were established and the adsorption phenomenon was described by the non-competitive Langmuir adsorption model which fitted well the experimental data. An evaluation of adsorption capability was carried out using model parameters which were graphically determined. Models for removal of cations have been discussed; they represent efficient tools for predicting the behaviour of the biosorbents in metal ion adsorption systems.
ACKNOWLEDGMENTS
The authors are grateful to Terrecor company (Meymac, France) for supplying the biological material. This work was supported by a grant of the firm “La Florentaise”, the “Agence Nationale de Valorisation de la Recherche” and the “Association pour le Développement Industriel et Economique du Massif Central et du Centre”.