Extraction of cesium and strontium into hydrocarbon solvents using tetra-C-alkyl cobalt dicarbollide

Tetra-C-alkyl derivatives of cobalt dicarbollide, Co(C2R2B9H9)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-hexyl4- in mesitylene and diethylbenzene compared to 0.01 M H+CoB2- in nitrobenzene. H+CoB2-hexyl4- in diethylbenzene shows improved selectivity (104) for Cs over Na in acidic solution. In dilute alkaline solution (0.01 M NaOH), H+CoB2-hexyl4- extracts Cs less efficiently, but more effectively removes Sr at higher base concentrations (1.0 M NaOH). Other aspects of the H+CoB2-hexyl4-/hydrocarbon performance are comparable to the previously known H+CoB2 nitrobenzene extractant. 13 refs., 8 figs