Radiostrontium Removal from Milk, Determination of Apparent Equilibrium Constants of the Exchange Reactions of Sodium, Potassium, Calcium, and Magnesium with Amberlite IR-120

The apparent equilibrium constants for the exchange reactions between resin and aqueous solutions containing Ca, K, Na, and Mg were determined for a series of total concentrations of the chlorides of the ions. The constants were used to calculate the required solution composition for charging the resin to a desired composition. A 2.1 x 30.5 cm column of Amberlite IR-120, originally in the H form, was equilibrated with solutions of the cations adjusted to pH 6.6. From determinations of the apparent equilibrium constants at different ionic strengths, the desired concentrations of the charging solutions could be calculated, in order to maintain the original cation composition of milk. The procedure has application for charging a resin so that it will be in equilibrium with milk when it is desirable to remove specific cations, such as Sr/sup 90/ or other cationic radionuclides, while leaving the other components unchanged. (TCO)