EFFECT OF CROWN-ETHERS ON THE ION-EXCHANGE BEHAVIOR OF ALKALINE-EARTHMETALS - TOWARD IMPROVED LON EXCHANGE METHODS FOR THE SEPARATION AND PRECONCENTRATION OF RADIUM

The effect of selected crown ethers on the uptake of alkaline earth ca tions by sulfonic acid and diphosphonic acid-based cation-exchange res ins from hydrochloric acid media is examined. The effect observed is s hown to vary with the hydrophobicity of the crown ether, Water-soluble crown ethers enhance the sorption of certain cations, thereby improvi ng the selectivity of the resin for other alkaline earths over calcium ion, an apparent result of a synergistic interaction between crown et her 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 c rown ether from the resin phase and the formation of cation-crown comp lexes in the solution phase, The result can be a reversal of the selec tivity sequence ordinarily exhibited by the resin.