Considerable interest has been shown during the past few years in the ion-eschange properties of zinc hexacyanoferrate(II)1-4, together with other hexacyanoferratesfi-14, since it was shown that this property may be exploited in the isolation of 137Cs from otherraclionuclides. The authors have separated amixtureof sodium, potassium, rubidiumand ccsium by thin-layer chromatography on a plate consisting of cellulose powder containing potassium zinc hesacyanoferrate(I1)
or sodium zinc hexacyanoferrate-(IL) in only xG min 16. However, when misturesof these ions were developedon a plate of cellulose powcIer containing zinc hexacyanofcrrate(I1) instead of sodium zinc hcxacyalloferrate(II), the resulting spots tailed and could not be separated from each other. Such different migration behaviors toward zinc hexacyanoferratc( II) analogucs have led to a study of their relative compositions and the discrepancy of their adsorption behavior for alkali metal ions. Since these analogues have an exceptionally strong affinity for ccsium ion, it was thought desirable to study in great detail an exchange involving this ion.
ESPERIMENTAL
Prejhwation of zinc Ite~acyanoferrate(1TI) amahgtces
All reagents used in this study were of analytical grade. The analogues were prepared by mixing o.z M sodium lle~acyanofe~ate(II) (zoo-300 ml) and 0.x it4 zinc nitrate at ratios of x : 3, I : 2.5, I : 2, I : 1.5 and I : I, respectively. The white slurries were obtained by adding these solutions dropwise and simultaneously into a. beaker for 30 min while stirring. They were heated with stirring on a boiling water bath for z h, allowed to stand for 24 11, filtered or centrifuged, washed thoroughly and dried at 60" for 24 h. Slurries other than the I : 3 ratio were finely dispersed, and were centrifuged for 3 min at 8000 g rather than filtered. The precipitates labelled with 22Na or ah% were prepared by the same procedure as unlabelled ones.
Xelative adsorfitios rate and batch distribrdion coefficient Zinc hexacyanoferrate(I1) analogues were compressed into pills under a pressure of about 300 kgfcmz, allowed to break down in water for several days, air-dried, and sieved to 200-300 mesh 1". The relative adsorption rates for cesium(1) were determined by mixing 20 mg of the analogues with 2 ml of aqueous solution containing cesium chloride tagged with i37Cs, followed by centrifugation at 8000 g for 3 min. The Ancrl. Clbiru. Ada, '+s) (1970) 317-322 KURAKU,K. KUROTAKI SUMMARY The dependence of the composition of zinc hexacyanoferrate(I1) complexes on A?d. Chir?l.