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  • Author or Editor: M. Daňková x
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Abstract  

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+(aq)+NaL+(nb)⇄ML+(nb)+Na+(aq) taking place in the two-phase water-nitrobenzene system (M+=Li+, K+, Rb+, Cs+; L=18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. The stability constants of the ML+ complexes in nitrobenzene saturated with water were calculated; they are found to increase in the cation order Cs+Li+Na+Rb+K+. Further, the individual extraction constants for the NaL+, KL+, RbL+ and CsL+ complex species in the wate-nitrobenzene system were determined; their values increase in the series Na+Rb+Cs+K+.

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Abstract  

Extraction of cesium by the nitrobenzene solution of sodium bis-1,2-dicarbollylcobaltate (Na+B) in the presence of 18-crown-6 (18C6, L) has been investigated. The equilibrium data have been explained assuming that the complexes NaL+, CsL+ and CsL2 + are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.

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Abstract  

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium 2Li+(aq)+SrL2 2+(nb) 2LiL+(nb)+Sr2+(aq) taking place in the two-phase water-nitrobenzene system (L=15-crown-5; aq=aqueous phase, nb=nitrobenzene phase) was evaluated as logK ex (2Li+;SrL2 2+)=−3.7. Further, the stability constant of the 15-crown-5—lithium complex in nitrobenzene saturated with water was calculated: log βnh(LiL+)=7.0.

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Abstract  

From extraction experiments with22Na as a tracer, the extraction constant corresponding to the equilibrium Ba2+(aq)+2NaL+(nb)⇄ ⇄BaL2 2+(nb)+2Na+(aq) taking place in the two-phase water-nitrobenzene system (L=15-crown-5; aq=aqueous phase, nb=nitrobenzene phase) was evaluated as logK ex (Ba2+,2NaL+)=3.3±0.1. Further, the stability constant of the complex BaL2 2+ in nitrobenzene saturated with water was calculated: log βnh(BaL 2 2+ )=16.4±0.1.

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Abstract  

From several strontium distribution experiments with 85Sr tracer, the extraction constant corresponding to the equilibrium Ca2+(aq)+SrL2+(nb) CaL2+(nb)+Sr2+ (aq) in the two-phase water-nitrobenzene system (L = 18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was tentatively evaluated as log K ex (Ca2+,SrL2+) = –1.9±0.1. Furthermore, the stability constant of the calcium — 18-crown-6 complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log nb(Cal2+) = 10.1±0.1.

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Abstract  

From the extraction experiments and -activity measurements, the extraction constant corresponding to the Rb+(aq)+CsL+(nb)RbL+(nb)+Cs+(aq) equilibrium in the two-phase water-nitrobenzene system (L=valinomycin; aq=aqueous phase, nb=nitrobenzene phase) was evaluated in the form logK ex (Rb+, CsL+)=0.9. Further, the stability constant of the valinomycin-rubidium complex in nitrobenzene saturated with water was calculated as log nb(RbL+)=11.7.

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