As one of the major constituents of fission products, barium has attracted considerable attention in recent years. Several ion-exchange methods have been applied to barium in this laboratory 1-3. Ion-exchange separations of barium from various elements, e.g. lead, strontium, radium and lanthanum, have been effected by different workers 4-1o.
MINAMI AND ISHIMORI 4 explored the possibility of separating barium from lead on a cation-exchanger by first eluting the adsorbed lead with ammonium acetate at pH 6.0 and then barium with lO% ammonium chloride. The difference in the stability of the anionic complexes of barium and lead with ethylenediaminetetraacetic acid at pH 4"5 and lO.5 respectively has been utilised for their separation 5 ; lead (pH 4"5) passed out of bed and the adsorbed barium was eluted with ethylenediaminetetraacetic acid (disodium salt) at pH 10.5. The anion-exchange separation 6 of lead from barium has been effected by adsorbing the anionic lead chloride complex on an anionite while barium passed through. The separation of barium from strontium has been done by govY AND DUYCKAERTST; the metals were eluted selectively with EDTA at varying pH. A direct method has been devisedS, 9 for the separation of barium from radium using 0.5 M ammonium citrate solution adjusted to pI~ 7.5-8.o. Selective elution with 5 % citric acid at pi ca. 4.0 permits the separation of lanthanum from barium 10.
However, systematic cation-exchange studies of barium have not been reported so far. The objective of this investigation was to carry out exploratory studies on the cation-exchange behaviour of barium on Dowex 5oW-X8 (hydrogen form). In the present paper nitric acid, hydrochloric acid, ammonium chloride, sodium nitrate, sodium chloride, ammonium acetate, citric acid, tartaric acid and EDTA have been studied as the eluting agents. Barium has been separated from uranium(VI), copper-(II), mercury(II), caesium, zinc, cadmium, silver, cerium(IV), zirconium, thorium, iron(III) and bismuth(III).
EXPERIMENTAL
Apparatus
Ion-exchange column and Cambridge pH indicator. The ion-exchange column was similar to that described previously 1-3. A resin bed 1.4 X 2o em was used.
Reagents
Barium nitrate solution (5 mg Ba/ml). 4,6115 g of barium nitrate (E. Merck) was dissolved in 5o0 ml of distilled water. The solution was standardised by the chromate method 11. Dowex