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.