Influence of aggregation on the extraction of trivalent lanthanide and actinide cations by purified Cyanex 272, Cyanex 301, and Cyanex 302

Jensen, Mark P.; Bond, Andrew H.

doi:10.1524/ract.2002.90.4_2002.205

Cited by 101 publications

(75 citation statements)

References 36 publications

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“…The most successful approaches to group separations developed to date have involved exploiting the slightly greater covalency of An 3þ -bonding interactions, which was first reported by Diamond et al [3]. This difference in bonding characteristics is coincident with the greater radial extension of the 5f orbitals (relative to the 4f orbitals in the lanthanides), though it is not yet clear that the effect is indicative of 6d orbital participation in metal-ligand bonding [4][5][6][7]. Interaction of nitrogen and sulfur donors with An 3þ is stronger than with Ln 3þ , thus potentially enabling a successful separation [5].…”

Section: Introductionmentioning

confidence: 99%

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The role of carboxylic acids in TALSQuEAK separations

Braley

Carter

Sinkov

et al. 2012

Journal of Coordination Chemistry

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Recent reports have indicated that Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes (TALSPEAK)-type separations chemistry can be improved through the replacement of bis-2-ethyl(hexyl) phosphoric acid (HDEHP) and diethylenetriamine-N,N,N 0 ,N 00 ,N 00 -pentaacetic acid (DTPA) with the weaker reagents 2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester (HEH [EHP]) and N-(2-hydroxyethyl) ethylenediamine-N,N 0 ,N 0 -triacetic acid (HEDTA), respectively. This modified TALSPEAK has been provided with an adjusted acronym of TALSQuEAK (Trivalent Actinide-Lanthanide Separation using Quicker Extractants and Aqueous Komplexes). Among several benefits, TALSQuEAK chemistry provides more rapid phase transfer kinetics, is less reliant on carboxylic acids to mediate lanthanide extraction, and allows a simplified thermodynamic description of the separations process that generally requires only parameters available in the literature to describe metal transfer. This article focuses on the role of carboxylic acids in aqueous ternary (M-HEDTA-carboxylate) complexes, americium/lanthanide separations, and extraction kinetics. Spectrophotometry (UV-Vis) of the Nd 3þ hypersensitive band indicates the presence of aqueous ternary Nd-Lac-HEDTA species (Lac ¼ lactate, K 111 ¼ 1.83 AE 0.01 at 1.0 mol L À1 ionic strength, Nd(HEDTA) þ Lac À À! À Nd(HEDTA)Lac À ). While lower levels (0.1 mol L À1 vs. 1.0 mol L À1 ) of carboxylic acid will still be necessary to control pH and encourage phase transfer of the heavier lanthanides, application of different carboxylic acids does not have an overwhelming impact on Ln/Am separations or extraction kinetics relative to conventional TALSPEAK separations. TALSQuEAK separations come to equilibrium in two to five minutes depending on the system pH using only 0.1 mol L À1 total lactate or citrate.

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Section: Introductionmentioning

confidence: 99%

“…Interaction of nitrogen and sulfur donors with An 3þ is stronger than with Ln 3þ , thus potentially enabling a successful separation [5]. This fundamental difference has inspired considerable research addressing the development of soft donor molecules or ions for separations applications [4,[7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

The role of carboxylic acids in TALSQuEAK separations

Braley

Carter

Sinkov

et al. 2012

Journal of Coordination Chemistry

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“…[11][12][13][14][15][16] The use of vapor pressure osmometry to examine unpurified Cyanex 301/heptane solutions has revealed that the extractant is present in monomeric form in the concentration range of 0.016-0.16 M. [12] However, J. Chen et. al., [13] using an interfacial distribution method for the aqueous and organic phases, demonstrated that pure Cyanex 301 is dimeric in heptane solutions in the concentration range of 0.2-1.0 M (pH 5 3.66).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the State of Bis(2,4,4‐Trimethylpentyl)dithiophosphinic Acid in Nonane and Toluene Solutions

Grigorieva¹,

Павленко²,

Pleshkov³

et al. 2009

Solvent Extraction and Ion Exchange

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An IR spectroscopy method is used to examine the state of nonane and toluene diluted bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR) in the concentration range of 0.025-1.0 M. It was found that in contrast to the ''inert'' solvent nonane, in which marked self-association of the dithiophosphinic acid due to the formation of intermolecular SH…S hydrogen bonds begins at an HR concentration of ,0.1 M, in the aromatic diluent toluene this process begins at HR total >0.4 M. This result is explained by the interaction of the proton of the S-H group of the dithiophosphinic acid with the p-electron system of the toluene aromatic ring and the formation of SH…p hydrogen bonds, preventing the self-association of the organic acid. The presence of the monomeric, dimeric, and tetrameric forms of the extractant in solution was shown to best describe the bis(2,4,4-trimethylpentyl)-dithiophosphinic acid-nonane system. The formation constants of the dimers (K 2 5 0.78 ¡ 0.07) and tetramers (K 4 5 3.42 ¡ 0.26) have been calculated.

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“…However, it is well known that the trivalent lanthanide and actinide ions possess about 8−9 molecules of water in the inner coordination sphere depending on the cation size. It is, however, reasonable to assume that about 9 water molecules are present in the inner coordination sphere of Am 3+ as well as Eu 3+ (18). Therefore, while forming the extractable complexes, the inner-sphere water molecules get replaced by the extractants, Cyanex 301 and terpy in the present case, to yield hydrophobic complexes which are easily extracted.…”

Section: Determination Of Thermodynamic Parametersmentioning

confidence: 85%

A Novel Solvent System Involving Terpyridine and Cyanex-301 for Am(III) and Eu(III) Separation from Weakly Acidic Feeds

Bhattacharyya

Mohapatra

2014

Separation Science and Technology

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Separation of trivalent actinides and lanthanides is a challenging task and has a great relevance in the nuclear fuel cycle. Bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301) show high selectivity for the trivalent actinides over the lanthanides at pH 3 or higher and N-donor ligands were reported to enhance the selectivity. 2,2 :6 ,6"-Terpyridine (terpy), on the other hand, has shown to be quite effective at lower pH values and the combination of Cyanex 301 and terpy was evaluated in the present study, for the first time, for the separation of Am(III) from Eu(III), representative actinide and lanthanide elements, respectively at pH 2.0.Thermodynamic parameters (enthalpy, entropy, and free energy) for the two phase extraction were also determined from the distribution studies at variable temperatures. Extraction of both Am 3+ and Eu 3+ was favored by negative enthalpy of extraction. More negative G value indicated that Am 3+ extraction was more favoured as compared to Eu 3+ extraction using this solvent system. Effect of diluent composition on the extraction of Am 3+ and Eu 3+ was also studied in the present work.

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Influence of aggregation on the extraction of trivalent lanthanide and actinide cations by purified Cyanex 272, Cyanex 301, and Cyanex 302

Cited by 101 publications

References 36 publications

The role of carboxylic acids in TALSQuEAK separations

The role of carboxylic acids in TALSQuEAK separations

Investigation of the State of Bis(2,4,4‐Trimethylpentyl)dithiophosphinic Acid in Nonane and Toluene Solutions

A Novel Solvent System Involving Terpyridine and Cyanex-301 for Am(III) and Eu(III) Separation from Weakly Acidic Feeds

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