Ion Flotation of Zinc(II) and Cadmium(II) in the Presence of Side-Armed Diphosphaza-16-Crown-6 Ethers

Abstract

Competitive flotation of zinc(II) and cadmium(II) ions from dilute aqueous solutions by side-armed lariat ether-type derivatives of diphosphaza-16-crown-6 ethers in the presence of nonylphenol nonylethylene glycol ether as the non-ionic foaming agent has been investigated. The influence of the type of group attached to the PNP-lariat ether molecule on the selectivity and efficiency of Zn(II) and Cd(II) ion flotation is studied. An effect of alkali metal cations, i.e., Li⁺ and Na⁺, on Cd(II) ion-flotation removal is also reported. It was shown that the removal of Cd²⁺ increases with increase of pH values and decreases with alkali metal cations concentration increase in aqueous solutions. The correlation between selectivity coefficients of Cd(II)/Zn(II) and pH of aqueous solution as well as molar intrinsic volume and hydrophilic–lipophilic balance of studied ethers was found.

Keywords:

• Ion flotation
• Zinc(II)
• Cadmium(II)
• Diphosphaza-16-crown-6 ethers

Acknowledgments

The authors would like to thank the Maria Sklodowska-Curie Fund II (grant PAN/NSF-97-307 for K. B and I. P-C.) and the Polish Science Foundation (grant 4 T09B107 22 for M.U. and W.W.) for financial support. We would also like to thank professor W. Apostoluk for calculation of correlation (6).