A procedure for preferential trapping of cesium cations from aqueous solutions and their separation from other inorganic cations

The title procedure is as follows. Deltahedral heteroborane anions are added to the aqueous solution containing cesium ions, precipitate (if any) is separated off, and the cesium salts involving the deltahedral heteroborane anions are trapped on activated carbon. The cobaltocarborane anion [3-Co-(1,2-C2B9H11)2] and/or its substitution derivatives are particularly well suited to this purpose. The process can find use in the separation of radionuclides present in waste solutions arising from spent nuclear fuel treatment. (P.A.). 1 fig