Crown ethers as size-selective synergists in solvent extraction systems: A new selectivity parameter

Kinard, W. F.; McDowell, W.J.

doi:10.1016/0022-1902(81)80648-3

Cited by 50 publications

(13 citation statements)

References 13 publications

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“…In our experiments, wider ranges of ton concentrations as well as ionic strength were studied. It allowed us to obtain the asymptotic plots at high concentration of nitric acid and yttrium nitrate, and to assume that at a total concentration of nitrate ions less than 6-7 M, variations of [NO 3 − ] affect strontium extraction more strongly than other factors, such as solution ionic strength. The higher nitrate ion concentration causes changes in the system state, leading to retardation of D Sr Fig.…”

Section: Strontium Distribution Studymentioning

confidence: 99%

“…To demonstrate this, strontium was extracted with 0.2 M DCH18C6 in n-octanol from a 5 M nitric acid solution and then stripped out with several portions of distilled water at V 0 : V aq = 2 : 1. For comparison, strontium was stripped out from the organic phase after its extraction from a 2 M Y(NO 3 ) 3 solution in 1 M HNO 3 . In the first case, 4 contacts were required to recover strontium completely, and only 3 contacts were needed in the second case (Table 3).…”

Section: Nitric Acid Extractionmentioning

confidence: 99%

“…This complex is weak if the crown ether is too small and the cation cannot enter the plane of oxygen atoms where the charge density is highest. If the crown ether is too large, then the cation cannot be simultaneously close to all the oxygen atoms -and this also weakens the complex bond [3].…”

Section: Introductionmentioning

confidence: 98%

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Separation of strontium from yttrium nitrate solutions by solvent extraction with dicyclohexano-18-crown-6

Kuznetsov¹,

Han²,

Park³

et al. 2001

Radiochimica Acta

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The extraction of strontium and yttrium by a 0.2 M solution of dicyclohexano-18-crown-6 (DCH18C6) in n-octanol from nitric acid solutions as well as from solutions of yttrium nitrate in nitric acid was studied. Increasing the nitric acid concentration within the 0.1-7 M range and yttrium nitrate concentration within the 0.1-2 M range considerably improves strontium extraction, increasing its distribution ratio up to 40. Meanwhile, the yttrium distribution ratio at these conditions does not exceed 0.05. High separation efficiency of strontium and yttrium at a high yttrium nitrate concentration allows considering DCH18C6 as a promising extractant for the process of n.c.a. 89 Sr isolation from fast neutron irradiated yttrium targets.

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Section: Strontium Distribution Studymentioning

confidence: 99%

Section: Nitric Acid Extractionmentioning

confidence: 99%

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Separation of strontium from yttrium nitrate solutions by solvent extraction with dicyclohexano-18-crown-6

Kuznetsov¹,

Han²,

Park³

et al. 2001

Radiochimica Acta

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“…[21][22][23] Thus, the good correspondence of the ionic diameter of Ra 2þ to the cavity size of the DCH21C7 provides no guarantee that the crown ether will serve as an effective synergist. [21][22][23] Thus, the good correspondence of the ionic diameter of Ra 2þ to the cavity size of the DCH21C7 provides no guarantee that the crown ether will serve as an effective synergist.…”

Section: Marcel Dekker Inc • 270 Madison Avenue • New York Ny 10016mentioning

confidence: 99%

Extraction of Alkaline Earth and Actinide Cations by Mixtures of Di(2-Ethylhexyl) Alkylenediphosphonic Acids and Neutral Synergists

McAlister

Chiarizia

Dietz

et al. 2002

Solvent Extraction and Ion Exchange

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The synergistic extraction of alkaline earth (Ca 2þ , Sr 2þ , Ba 2þ and Ra 2þ ) and actinide (Am 3þ , UO 2 2þ and Th 4þ ) cations from aqueous nitric acid solutions by mixtures of P,P 0 -di (2-ethylhexyl) Downloaded by [Erciyes University] at 07:34 26 December 2014 methylene-(H 2 DEH[MDP]), ethylene-(H 2 DEH[EDP]), and butylene-(H 2 DEH[BuDP]) diphosphonic acids and neutral extractants in o-xylene has been investigated. The cis-syn-cis and cis-anti-cis stereoisomers of dicyclohexano-18-crown-6 (DCH18C6), the unsubstituted 21-crown-7 (21C7) and dicyclohexano-21-crown-7 (DCH21C7) were used as neutral synergists of the crown ether type. For Am(III) synergistic effects were also investigated using neutral organophosphorus esters, such as, tri-n-butylphosphate (TBP), diamyl amylphosphonate (DA[AP]) and tri-n-octylphosphine oxide (TOPO) as co-extractants. In all systems investigated, no synergistic extraction enhancement was observed for actinide ions. For the alkaline earth cations, synergistic effects were only observed when mixtures of H 2 DEH [EDP] or H 2 DEH-[BuDP] with DCH18C6 were used to extract Sr 2þ , Ba 2þ and Ra 2þ . No synergistic effects were observed for the extraction of alkaline earth cations by H 2 DEH [MDP] or for the extraction of Ca 2þ by any of the diphosphonic acids studied. The synergistic effects obtained with DCH18C6 were significantly higher for the cis-syn-cis than for the cis-anti-cis stereoisomer. 448MCALISTER ET AL.

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“…Distribution coefficients of some fission products: (In brackets: cavity diameter[13]) Org. Phase: Ο.ΙΛί crown compound-0.17Λί picric acid-nitrobenzene.…”

mentioning

confidence: 99%

Extraction of Sodium and some Fission Products with Crown Ethers

Jalhoom¹,

Mani²,

Hassan³

1985

Radiochimica Acta

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The extraction of le3 Ru, 133 Ba, 137 Cs,14, Ce, 152 Eu in addition to "Na has been studied using six crown compounds of different cavity sizes and substitutions in nitrobenzene. Ruthenium is not extracted and thus can be separated in picrate media from other nuclides by applying methanol in the aqueous phase and picric acid in the organic phase. Barium is extracted quantitatively with dicyclohexyl-18-crown-6 independent of the organic solvents and can be separated selectively in non-polar solvents.

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Crown ethers as size-selective synergists in solvent extraction systems: A new selectivity parameter

Cited by 50 publications

References 13 publications

Separation of strontium from yttrium nitrate solutions by solvent extraction with dicyclohexano-18-crown-6

Separation of strontium from yttrium nitrate solutions by solvent extraction with dicyclohexano-18-crown-6

Extraction of Alkaline Earth and Actinide Cations by Mixtures of Di(2-Ethylhexyl) Alkylenediphosphonic Acids and Neutral Synergists

Extraction of Sodium and some Fission Products with Crown Ethers

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