Heavy metal uptake from aqueous solution by cork and yohimbe bark wastes

In this work the ability of cork and yohimbe bark wastes to remove Cu(II) a nd Ni(II) from aqueous solutions has been studied. The influence of pH, sod ium chloride and metal concentration on metal uptake was investigated. Meta l uptake showed a pH-dependent profile. Maximum sorption for both metals wa s found to occur at around pH 6-7. In the case of cork an increase of sodiu m chloride concentration provoked a decrease in metal removal. Adsorption i sotherms at the optimum pH were expressed by the non-competitive Langmuir a dsorption model, and model parameters were determined. It was seen that the adsorption equilibrium data fitted very well to the model in the concentra tion range studied. When comparing both biomaterials, yohimbe bark waste wa s found to be the most efficient adsorbent for both metals studied. (C) 200 0 Society of Chemical Industry.