[en] Preparation and use of tetra-C-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents. Tetra-C-alkyl derivatives of cobalt dicarbollide, Co(C₂R₂B₉H₉)₂^-(CoB₂R₄^-; R=CH₃ and C₆H₁₃) are demonstrated to be significant cesium and strontium extractants from acidic and alkaline solutions into non-toxic organic solvent systems. Extractions using mesitylene and diethylbenzene are compared to those with nitrobenzene as the organic phase. CoB₂-hexyl₄^- in diethylbenzene shows improved selectivity (10⁴) for Cs over Na in acidic solution. In dilute alkaline solution, CoB₂-hexyl₄^- extracts Cs less efficiently, but more effectively removes Sr from higher base concentrations. A general synthesis of tetra-C-alkyl cobalt dicarbollides is described. 6 figs

[en] Processing of defense-related nuclear wastes requires separation of the highly radioactive fission products cesium and strontium from both acidic and alkaline waste streams. The cobalt dicarbollide process, while known to be efficient and selective for Cs and Sr removal from acidic wastes, has received little attention in this country due to the use of toxic nitrobenzene as diluent. By preparing alkyl-functionalized cobalt dicarbollide derivatives, we have developed a system that utilizes non-hazardous, inexpensive hydrocarbons as diluents. The performance of this system in acidic and alkaline media, including distribution coefficients, selectivity over relevant cations, capacity, and chemical stability, will be discussed

[en] 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

[en] The determination of K_d for UO₂⁺² has been determined in nitric acid solutions between 1.00 and 10.0 M at 20 degrees C. The distribution constant, K_d, is defined as [(RUO₂(NO₃)_x^-(x-2)/UO₂(NO₃)_x^-(x-2))_total] x [solution volume/dry resin mass] (mL/g), where (RUO₂(NO₃)_x^-(x-2) represent the U(VI) sorbed on the Reillex -HPQ anion exchange resin and (UO₂(NO₃)_x^-(x-2)_total is the U(VI) in solution. Equilibrium is attained between the resin and the UO₂⁺² solution in 30 minutes or less. The K_d maximizes at 7.5 M HNO₃ with a value 14.6 mL/g. In 1.0 M HNO₃ and 0.0100 to 4.5 M NaNO₃, K_d maximizes at 4.0 M total NO₃^- with a value 14.1 mL/g. In 1.0 M HNO₃ and 0.0030 to 2.17 M Al(NO₃)₃, K_d maximizes at 7.5 M total NO₃^- with a value 36.6 mL/g. The K_d-[NO₃^-] plots are bell shaped curves that are interpreted to imply that K_d increases as UO₂(NO₃)₃^- is sorbed onto the resin and decreases as the NO₃^- ion displaces it. Similar behavior has been observed for Dowex -1. In 1.0-9.5 M hydrochloric acid solutions, a maximum value of K_d of 1890 mL/g occurs at 8.00 M for UO₂⁺². For U(IV), a maximum value of K_d of 23120 mL/g occurs at 8.25 M. The same shape curves are observed and a similar interpretation is given. The numerical results of the modeling are presented