EXTRACTION OF CESIUM AND STRONTIUM INTO HYDROCARBON SOLVENTS USING TETRA-C-ALKYL COBALT DICARBOLLIDE

Tetra-C-alkyl derivatives of cobalt dicarbollide, Co(C(2)R(2)B(9)H(9))(2)(-) (CoB2-R4(-); R = CH3, C6H13) are examined as potential cesium and strontium extractants for acidic and alkaline solutions. The mechanism of cobalt dicarbollide extraction is characterized, and extended into new non-toxic solvent systems. Extractions using 0.01 M H+CoB2-hexyl(4)(-) in mesitylene and diethylbenzene are compared to 0.01 M H+CoB2- in nitrobenzene. H(+)CoB2(-)hexyl4(-) in diethylbenzene shows improved selectivity (10(4)) for Cs over Na in acidic solution. In dilute alkaline solution (0.01 M NaOH), H+CoB2-hexyl(4)(-) extracts Cs less efficiently, but more effectively removes Sr at higher base concentrations (1.0 M NaOH). Other aspects of the H+CoB2-hexyl(4)(-)/hydrocarbon performace are comparable to the previously known H+CoB2-/nitrobenzene extractant.