In vitro Study of 137Cs Sorption by Hexacyanoferrates(II)

We synthesized a variety o f colloidal and non-colloidal mixed hexacyanoferrate(II) com plexes of Fe, C u, C o, Ni, Z n . Mn and studied the cesium sorption in vitro under physiological conditions (artificial gastric juice. pH 1.2 and artificial duodenal ju ice. pH 6.8). All of the hexacyanoferrates under study (except cesium iron (III) hexacyanoferrate C sFeH C F) sorb tracer am ounts of 1'7Cs quantitatively . D ifferences in the sorption capacity becom e obvious by offering substantial am ounts of cesium. Potassium copper hexacyanoferrate (II) (K C uH C F) and potassium zinc hexacyanoferra te(II) (K Z nH C F ) are most efficient in cesium sorption at pH 1.2 and at pH 6.8. The sorption capacities of K C uH C F and K Z nH C F (2.3 —3.0 mmol Cs/g H C F) are twice as high as for colloidal Prussian blue (K F eH C F ; 1.0—1.3 m mol Cs/g H C F) and insoluble Prussian blue (FeH C F ; 1.0—1.6 m mol Cs/g H C F). T he most prom ising com pounds, K C uH C F and K Z nH C F, should be fu rth er investigated in in vivo studies for 137134cesium decorporation . Evidence indicate that the sorption m echanism for most of the com pounds under study is a cesium /potassium ion-exchange reaction. In the case of insoluble Prussian blue (F eH C F ), a cesium /proton exchange was observed. O n laborato ry scale, 137 l34C s-contam inated whey dry pow der, produced from South G erm an cow m ilk in sum m er 1986 was alm ost com pletely decontam inated by dialysing a whey suspension against buffer solution contain ing FeH C F. The 137 l34C s+-ions, com pletely bound by FeH C F . can be isolated from the buffer solution by sim ple filtration . The buffer solution and the FeH C F can be re-used several times.