Extraction Of Trivalent Actinides Research Articles

Complexation and extraction of trivalent actinides over lanthanides using highly soluble phenanthroline diamide ligands with different side chains

Although phenanthroline diamide ligands have been widely reported, their limited solubility in organic solvents and poor performance in the separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) at high acidity are still clear demerits. In this study, we designed and synthesized three highly soluble phenanthroline diamide ligands with different side chains. By introducing alkyl chains and ester groups, the ligands solubility in 3-nitrotrifluorotoluene is increased to over 600 mmol/L, significantly higher than the previous reported phenanthroline diamide ligands. Based on anomalous aryl strengthening, benzene ring was incorporated to enhance ligand selectivity toward Am(III). Extraction experiments demonstrated favorable selectivity of all the three ligands towards Am(III). The optimal separation factor (SFAm/Eu) reaches 53 at 4 mol/L HNO3, representing one of the most effective separation of An(III) over Ln(III) under high acidity. Slope analysis, single crystal structure analysis, as well as titration of ultraviolet visible spectroscopy, mass spectrometry, and nuclear magnetic resonanc confirmed the formation of 1:1 and 1:2 complex species between the metal ions and the ligands depending on the molar ratio of metal ions in the reaction mixture. The findings of this study offer valuable insights for developing phenanthroline diamide ligands for An(III)/Ln(III) separation.

The extraction of trivalent actinides and lanthanides by a novel unsymmetrical diglycolamide

The extraction of trivalent actinides and lanthanides by a novel unsymmetrical diglycolamide

Role of TBP on the extraction of trivalent f-cations with CMPO dissolved in a room temperature ionic liquid

ABSTRACTA detailed study on solvent extraction and optical spectroscopy was performed to understand the extraction of trivalent actinides by the solutions of CMPO (octylphenyl-N,N-diisobutyl-carbamoyl methyl phosphine oxide) in a room temperature ionic liquid (RTIL), viz. 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [C4mim][NTf2]. Solvent extraction studies of Am(III) from nitric acid solution indicated an ion-exchange extraction mechanism. Slope analyses on the distribution data revealed that the stoichiometry of the extracted complex of Am3+/CMPO changed from 1:3 (Am/CMPO) in the absence of tri-n-butyl phosphate (TBP) to 1:2 in the presence of TBP. The distribution ratio values of Am(III) decreased significantly in the presence of TBP suggesting that the latter has an important role in the complexation of CMPO with the metal ion. The extraction of acid increased many folds in the presence of TBP as compared to the bare CMPO solution. The absorption and emission spectra of the extracted complex in RTIL differ significantly in the presence and absence of TBP, signifying the role of TBP in the CMPO-RTIL solvent.

Influence of complexing species on the extraction of trivalent actinides from lanthanides with CyMe4–BTBP: a theoretical study

We studied geometric and electronic structures as well as thermodynamic properties of complexes [M(CyMe4–BTBP)2(NO3)]2+ and [M(CyMe4–BTBP)2]3+ with M = Am(III), Cm(III) and Ln(III) (La–Lu) theoretically. The actinide–nitrogen bonding is principally ionic with higher covalency in An–N bonds than in the Ln–N analogues. The selectivity towards An(III) over Ln(III) (La, Ce, Pr, Pm, Sm, Eu and Yb) is influenced by formed complexes to different extents by comparison of changes of Gibbs free energy of reaction, ΔΔGAm/Ln, for formation of [AmL2]3+/[LnL2]3+, [AmL2(NO3)]2+/[LnL2(NO3)]2+, and [AmL2(NO3)]2+/[LnL2]3+. The Am(III) selectivity is enhanced for [AmL2(NO3)]2+/[LnL2]3+ over [AmL2]3+/[LnL2]3+.

Process Development and Laboratory-Scale Demonstration of a Regular-SANEX Process Using C5-BPP (2,6-Bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine)

An optimized solvent comprising 0.01 mol/L C5-BPP + 0.5 mol/L 2-bromo-hexanoic acid in TPH with 10% 1-octanol was developed for the selective extraction of trivalent actinides from lanthanides. Equilibrium extraction data and kinetics of the system in extraction, scrubbing and stripping modes were evaluated and a 16-stage flow-sheet was successfully tested in a spiked centrifugal contactor demonstration. It turned out that 16 stages were insufficient for a complete recovery of An(III), although a clean An(III) product was obtained. The high selectivity of C5-BPP for An(III) was shown. The results of the spiked centrifugal contactor test are presented and discussed.

Reactions of ligands from BT(B)P family with solvated electrons and benzophenone ketyl radicals in 1-octanol solutions. Pulse radiolysis study

Pulse radiolysis involving reactions of solvated electrons and benzophenone ketyl radicals in 1-octanol with selected compounds from bis-triazinyl pyridines and bis-triazinyl bipyridines, BT(B)P family, developed for extraction of trivalent actinides have been studied. The designated ligands were: 2,6-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo-[1,2,4]triazin-3-yl)pyridine, 6,6′-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo-[1,2,4-]triazin-3-yl)-[2,2′]bipyridine, 6,6′-bis(5,6-diethyl-[1,2,4]triazin-3-yl)-[2,2′]bipyridine and 6,6′-bis(5,6-dipentyl-[1,2,4]triazin-3-yl)-[2,2′]bipyridine. Reactions of the ligands with solvated electrons in 1-octanol are fast. The rate constants were determined as equal to: $$ k_{{{\text{CyMe}}_{4} {\text{BTP}}}} . $$ = (2.4 ± 0.2) × 109 dm3 mol−1 s−1, $$ k_{{{\text{CyMe}}_{ 4} {\text{BTBP}}}} $$ = (1.7 ± 0.3) × 109 dm3 mol−1 s−1, $$ k_{{{\text{C}}_{ 2} {\text{BTBP}}}} $$ = (1.3 ± 0.3) × 109 dm3 mol−1 s−1 and $$ k_{{{\text{C}}_{ 5} {\text{BTBP}}}} $$ = (1.7 ± 0.3) × 109 dm3 mol−1 s−1. Reactions of the ligands with benzophenone ketyl radicals are much slower and the measured rate constants were as follows: $$ k_{{{\text{CyMe}}_{ 4} {\text{BTP}}}} $$ = 6.7 × 107 dm3 mol−1 s−1 and $$ k_{{{\text{CyMe}}_{ 4} {\text{BTBP}}}} $$ = 3.2 × 107 dm3 mol−1 s−1.

Comparative Evaluation of CMPO and Diglycolamide Based Solvent Systems for Actinide Partitioning in Mixer-Settler Runs Using Tracer-Spiked PHWR Simulated High Level Waste

The TRUEX solvent (0.2 M CMPO + 1.2 M TBP) was employed for countercurrent extraction studies with radiotracers spiked pressurized heavy water reactor simulated high level waste (PHWR-SHLW) employing a 12-stage of mixer-settler. The results of the mixer-settler runs with CMPO were compared with those obtained under identical conditions employing TODGA (N,N,N’,N’-tetraoctyl diglycolamide) and T2EHDGA (N,N,N’,N’-tetra-2-ethylhexyl diglycolamide) as the extractants. Even though the TRUEX solvent revealed quantitative extraction of trivalent actinides and lanthanides in 5 stages at O/A = 1, stripping of the extracted metal ions from the loaded organic phase was poor with dilute HNO3 solution (0.2 M HNO3). Quantitative stripping could not be achieved in 12 stages even when a complexing solution (0.1 M citric acid + 0.1 M HNO3) was employed as the strippant. In contrast, the stripping from loaded TODGA and T2EHDGA solvents was possible in < 6 stages with 0.2 M HNO3. The experimental results suggested that the performance of TRUEX solvent was inferior to the diglycolamide based extractants such as TODGA and T2EHDGA.

ChemInform Abstract: Complexation and Extraction of Trivalent Actinides and Lanthanides by Triazinylpyridine N‐Donor Ligands

AbstractReview: 183 refs.

Complexation and Extraction of Trivalent Actinides and Lanthanides by Triazinylpyridine N-Donor Ligands

Complexation and Extraction of Trivalent Actinides and Lanthanides by Triazinylpyridine <i>N</i>-Donor Ligands

Use of Polyaminocarboxylic Acids as Hydrophilic Masking Agents for Fission Products in Actinide Partitioning Processes

During the partitioning of trivalent actinides from High Active Raffinate (HAR) solutions, most processes have to cope with an undesirable co-extraction of some of the fission products. Four hydrophilic complexing agents of the group of polyaminocarboxylic acids, namely EDTA, HEDTA, DTPA, and CTDA were tested and compared for their ability to complex fission products in a simulated PUREX raffinate solution, thereby preventing their extraction into an organic solvent. Several solvents, based on TODGA and the DIAMEX reference molecule DMDOHEMA, that are commonly known to show quite high Zr and Pd co-extraction, were studied. Our investigations ultimately resulted in a substitution of oxalic acid and HEDTA by cyclohexanediaminetetraacetic acid (CDTA). A small addition of this hydrophilic complexing agent to the feed decreased the distribution ratios of Zr from 100 to <0.01. The suppression of Pd was also very effective, resulting in >90% of the metal retained in the feed solution. The extraction of trivalent actinides and lanthanides was not negatively affected by the presence of CDTA. Furthermore, experiments with high concentrations of Zr proved the applicability of this new masking agent. The suppression of Zr and Pd extraction was also verified at a high Pu loading which makes CDTA as a masking agent attractive for grouped actinide extraction processes (GANEX) as well as DIAMEX-SANEX type separations.

Synergistic Enhancement of the Extraction of Trivalent Lanthanides and Actinides by Tetra‐(n‐Octyl)Diglycolamide from Chloride Media

This work describes a unique synergistic enhancement of the extraction of trivalent actinides and lanthanides by extraction chromatographic resins containing tetra‐n‐octyldiglycolamide (TODGA) from hydrochloric acid containing anionic metal chlorides. The presence of mg/L quantities of trivalent Fe, Ga, In, Tl, or Bi in HCl leads to several orders of magnitude enhancement of the extraction of trivalent actinides and lanthanides. The synergistic effect persists, even when the amount of metal chloride exceeds the capacity of the resin. The application of this synergistic enhancement for the separation of actinium from stainless steel and the preconcentration of americium and plutonium from large soil samples will be described.

MINOR ACTINIDE PARTITIONING BY LIQUID–LIQUID EXTRACTION: USING A SYNERGISTIC MIXTURE OF BIS(CHLOROPHENYL)-DITHIOPHOSPHINIC ACID AND TOPO IN A HOLLOW FIBER MODULE FOR AMERICIUM(II)–LANTHANIDES(III) SEPARATION

Regarding the difficult selective extraction of trivalent actinides over fission lanthanides from acidic media, we performed several separation tests in hollow fiber modules. Using a synergistic mixture of bis(chlorophenyl)dithiophosphinic acid and tri-n-octyl phosphine oxide in tert-butyl benzene, tests on extraction, lanthanide scrubbing, and stripping were performed. Up to 99.99% americium could be extracted from 0.5 kmol/m3 nitric acid, with approximately one third of the lanthanides being co-extracted. Mass transfer calculations using a consistent set of input data showed good agreement with the experiments. The influence of operating mode on extraction efficiency was very pronounced. This is discussed based on the calculations.

SYNERGISTIC SOLVENT EXTRACTION OF TRIVALENT AMERICIUM AND EUROPIUM BY 2-BROMODECANOIC ACID AND NEUTRAL NITROGEN-CONTAINING REAGENTS

ABSTRACT The synergistic enhancement in the extraction of trivalent actinides (Am and Cm) and some lanthanides by 2-bromodecanoic acid and different nitrogen-containing extractants was studied. The extraction by mixtures of 2-bromodecanoic acid and 2,2′:6′,2″-terpyridine or N,N′-dimethyl-N,N′-dicyclohexyltetradecyl malonamide (DMDCHTDMA) respectively, in tert-butylbenzene (TBB) or hydrogenated tetrapropene (TPH), was investigated and compared with 2,4,6-tri-(2-pyridyl)-l,3,5-triazine (TPTZ) in synergy with 2-bromodecanoic acid. The synergistic enhancement and the separation factor between americium and europium was higher with the terpyridine mixture compared with the malonamide mixture. The separation factor between americium and europium from nitric acid (0·01 M) with terpyridine (0·02 M), 2-bromodecanoic acid (1 M ) in TBB was determined to be 7, while the separation factor for malonamide (0·1 M), 2-bromodecanoic acid (1 M) in TBB was approximately 3. This might indicate a more covalent character in the actinide-terpyridine complex than in the actinide-malonamide complex. The terpyridine was shown to be easily transferred to the aqueous phase when protonated and thus the protonation ability for terpyridine was investigated at different concentrations of terpyridine and 2-bromodecanoic acid. Studies to determine the stoichiometry

Liquid-liquid extraction of trivalent actinides and lanthanides with mixtures of N-benzoyl-N-phenyl hydroxylamine and neutral donors

Extraction of trivalent actinides Am and Cm and trivalent lanthanides Pm and Eu has been studied with mixtures of N-benzoyl-N-phenyl hydroxylamine (HBPHA) and TBP, TOPO or dipy in chloroform. The order of synergistic extraction was found to be TBP>TOPO>dipy, which is just the reverse to the order of basicity of these neutral donors. The interaction of HBPHA with TBP has been studied in chloroform. The synergistic species extracted was found to be M(BPHA)3·n TBP (n=1 or 2). Log D vs pH plots (at fixed HBPHA and TBP concentrations) gave straight lines with slopes 1.4 (Am, Cm, Pm) and 1.7 (Eu) instead of the expected value of 3.0. Reasons for these abnormalities are discussed.

Liquid-liquid extraction of trivalent actinides and lanthanides with 1-phenyl-3-methyl-4- trifluoroacetyl pyrazolone-5

Abstract Extraction of the trivalent actinides Am, Cm and Cf and lanthanides Eu, Tb, Tm and Lu has been studied with 1-phenyl-3-methyl-4-trifluoroacetyl pyrazolone- 5(HPMTFP) in chloroform and benzene. The formation of a self-adduct species M(PMTFP)3·HPMTFP has been observed with Am, Cm and Eu but only the chelate species M(PMTFP)3 with Cf, Tb, Tm and Lu. The reasons for the formation of a self-adduct species with lighter actinides and lanthanides and not with the heavier ones of the pyrazolones have been discussed.

Extraction of trivalent actinides and lanthanides by mixtures of HDDNS and crown ethers

Extraction of trivalent actinides and lanthanides by mixtures of HDDNS and crown ethers

Liquid-Liquid Extraction of Trivalent Actinides and Lanthanides with N-Benzoyl-N-Phenyl Hydroxylamine

Liquid-Liquid Extraction of Trivalent Actinides and Lanthanides with N-Benzoyl-N-Phenyl Hydroxylamine

Use of higher oxidation states of trans-plutonium elements for their determination

Use of higher oxidation states of trans-plutonium elements for their determination

Extraction of trivalent actinides with some substituted pyrazolones and their synergistic mixtures with tri- n-octylphosphine oxide in chloroform

Trivalent actinides, Am, Cm, Bk and Cf, have been extracted with 1-phenyl-3-methyl-4-benzoyl pyrazolone-5 (HPMBP) or 1-phenyl-3-methyl-4-(3:5-dinitrobenzoyl) pyrazolone-5 (HDMPP) in chloroform. With HPMBP, Am, Bk and Cf are extracted as the self-adduct species M(PMBP) 3· nHPMBP ( n = 1 or 2) whereas in all the other systems formation of a non-adduct chelate species has been observed. With tri- n-octylphosphine oxide (TOPO), as the neutral donor, the synergistic adduct species are M(A) 3· mTOPO, where m is 1 or 2 in the above systems. The equilibrium constants (β 1, β 2 and K 2) for the organic-phase synergistic reactions have been calculated. In Am(III)-different β-diketones-TOPO systems the equilibrium constants follow the order HPMBP < HDMPP < thenoyltrifluoroacetone < benzoyltrifluoroacetone.

Synergistic Extraction of Trivalent Actinides by Mixtures of 1-Phenyl-3-methyl-4-benzoyl-pyrazolone-5 and Neutral Oxo Donors

Abstract The synergistic extraction of trivalent actinides Am, Cm, Bk, and Cf with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and TBP or TOPO has been investigated in xylene at 30°C. With HPMBP alone, all four trivalent actinides form M(PMBP)3· HPMBP-type self-adducts. Bk(III) shows an abnormally high extraction with HPMBP alone. With TBP or TOPO(S) as neutral donor, except in the Bk/HPMBP/TBP system where Bk(PMBP)3· HPMBP·TBP was extracted, all metal ions were extracted as M(PMBP)3·S and M(PMBP)3·(S)2 into the organic phase. The equilibrium constants (β1, β2, and K 2 for the organic phase synergistic reactions have been calculated. The β1, β2 values for Bk(III)/HPMBP/TOPO system are much lower as compared to the corresponding values for other trivalent actinides. The reasons for this extraordinary behavior of Bk(III) have been discussed. The extraction behavior of the M(III)/HPMBP/S and the M(III)/HTTA/S systems has also been compared.