title: Effect of crown ethers on the ion-exchange behavior of alkaline Earth metals. Toward improved ion-exchange methods for the separation and preconcentration of radium.
abstract: The effect of selected crown ethers on the uptake of alkaline earth cations by sulfonic acid and diphosphonic acid-based cation-exchange resins from hydrochloric acid media is examined. The effect observed is shown to vary with the hydrophobicity of the crown ether. Water-soluble crown ethers enhance the sorption of certain cations, thereby improving the selectivity of the resin for other alkaline earths over calcium ion, an apparent result of a synergistic interaction between crown ether present in the resin phase and the ionic functional groups of the resin. In the presence of more hydrophobic crown ethers, a decrease in cation sorption is often observed, a result of the exclusion of the crown ether from the resin phase and the formation of cation-crown complexes in the solution phase. The result can be a reversal of the selectivity sequence ordinarily exhibited by the resin.
authors.affiliation: Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439.
authors.forename: M L
authors.initials: ML
authors.lastname: Dietz
authors.forename: R
authors.initials: R
authors.lastname: Chiarizia
authors.forename: E P
authors.initials: EP
authors.lastname: Horwitz
authors.forename: R A
authors.initials: RA
authors.lastname: Bartsch
authors.forename: V
authors.initials: V
authors.lastname: Talanov