Radium

Abstract

RADIUMTRACES of radium are best isolated by coprecipitation with barium sulphate, or other insoluble salts, and then the radiometric assay of radium can be performed directly, or after its separation from the collector. For this purpose, cation exchange methods have proved to be most suitable. Separation on Ion ExchangersPractically all methods hitherto developed for the separation of radium from other elements by means of ion exchange are based on its retention by cation exchange resins from dilute acid, neutral, or weakly alkaline solutions, in the presence or absence of complexing agents. Among these complexing agents, EDTA is the most suitable for the separation of radium from barium and the other alkaline earth metals, because in such media the separation factor is significantly larger than in solutions containing citrate, lactate, acetate, formate or dilute mineral acids. When the pH of the solution is raised to 9 or higher, radium, in the presence of EDTA, is not appreciably adsorbed and thus can be eluted under these conditions. For example, in 0-01 Μ EDTA, the distribution coefficients of barium and radium on Dowex 50, X8 are respectively about 1-2 and 9 at pH 8-8, and much less than 0-5 and about 0-6 at pH 10-5.(1 )