Ion Exchange Behavior of Cadmium, Mercury, Silver and Zinc on Retardion 11A8 and Chelex 100 Ion Exchangers in Ammonia Medium and Its Application for Radiochemical Separations

The ion exchange behavior of cadmium, zinc, mercury and silver in ammonia medium on Retardion 11A8 and Chelex 100 resins containing weakly acidic cation exchange groups of complexing properties has been investigated. The results revealed that apart from a simple replacement of counter-ions, sorption of these elements is accompanied by complex formation with the functional groups of the ion exchanger. The general quantitative relationship between the mass distribution coefficient of a given metal (*lMe) and concentration of ammonia (CNH3) has been derived. If a complex formation reaction in the stationary phase occurs, *lMe decreases with the increase of CNH3. The absolute value of the slope of the dependence log*lMe - log[NH3] corresponds to the average number of ammonia molecules displaced by the functional groups from the coordination sphere of the central ion. Examples of the use of Retardion 11A8 as well as Chelex 100 for the separation of trace amounts of Cd, Zn, Hg and Ag are presented.