PROCESS FOR SEPARATING CESIUM IONS FROM AQUEOUS SOLUTIONS BY USING AN ADDITION COMPOUND CONSISTING OF A MACROCYCLIC POLYETHER AND AN INORGANIC HETEROPOLYACID

A process for the extraction of cesium ions from an aqueous solution with an adduct compound containing a macrocyclical polyether and an inorganic heteropoly acid component. An organic phase in the form of a solution of an adduct compound in a polar organic solvent is prepared. The adduct compound is the product of a crown ether containing at least one species of the structural elements I II +TR III where, in structure I, n represents one of the numbers 0, 1 or 2, the -C-(C)n-O group forms part of the polyether ring and R1 is H,CH3, phenyl up to 4 R1( NOTEQUAL H); in structure II, the -C-C-O- group forms part of the polyether ring and R2 is H,CH3, t-butyl, pentyl, heptyl, nonyl, (CH2)9Ch3, phenyl up to 2 R2( NOTEQUAL H);and in structure III, the -C=C-O group forms part of the polyether ring and R3 is H,CH3, t-butyl, pentyl, heptyl, nonyl, (CH2)9CH9, phenyl up to 2 R3( NOTEQUAL H); with (b) an inorganic heteropoly acid, which is stable in a strongly acid and oxidizing medium, or a salt of the inorganic heteropoly acid. The aqueous solution containing the cesium ions is brought into contact with the adduct compound to extract the cesium from the aqueous phase into the organic phase. The organic phase charged with cesium ions is separated from the aqueous solution.