UPTAKE OF METAL IONS BY A NEW CHELATING ION-EXCHANGE RESIN. VII. ALKALINE EARTH CATIONS∗∗

ABSTRACT The comparison among the uptake of alkaline earth cations from dilute acidic solutions by the Diphonix™ resin, a silica based Diphonix-like resin, and a sulfonic type strong acid ion exchange resin has shown that the alkaline earth cations at tracer level concentration are retained by the Diphonix resin because they are bound mainly to the diphosphonic acid groups of the resin. Consequently, a dual-mechanism of access and recognition can be assumed to be operative in the uptake of the Group Ila cations by the Diphonix resin. A similar conclusion had been previously reached for the uptake of actinide ions based on the shape of their acid dependencies. Infrared spectra of the Diphonix resin and some of its metal salts have shown that the alkaline earth cations are bound to the diphosphonic acid groups through highly ionic interactions.