skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Acid-switched Eu(III) coordination inside reverse aggregates: Insights into a synergistic liquid-liquid extraction system

Authors:
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1349911
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganica Chimica Acta; Journal Volume: 460
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Ellis, Ross J. Acid-switched Eu(III) coordination inside reverse aggregates: Insights into a synergistic liquid-liquid extraction system. United States: N. p., 2017. Web. doi:10.1016/j.ica.2016.08.008.
Ellis, Ross J. Acid-switched Eu(III) coordination inside reverse aggregates: Insights into a synergistic liquid-liquid extraction system. United States. doi:10.1016/j.ica.2016.08.008.
Ellis, Ross J. Sat . "Acid-switched Eu(III) coordination inside reverse aggregates: Insights into a synergistic liquid-liquid extraction system". United States. doi:10.1016/j.ica.2016.08.008.
@article{osti_1349911,
title = {Acid-switched Eu(III) coordination inside reverse aggregates: Insights into a synergistic liquid-liquid extraction system},
author = {Ellis, Ross J.},
abstractNote = {},
doi = {10.1016/j.ica.2016.08.008},
journal = {Inorganica Chimica Acta},
number = ,
volume = 460,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
  • Determining the structure of complex solutions bearing metal ions is challenging, but crucial for developing important technologies such as liquid-liquid extraction for metal refining and separation purposes. Herein, the structure of an organic Eu(III) solution consisting a binary mixture of lipophilic ligands di-2-ethylhexyl phosphoric acid (HDEHP) and tetraoctyl diglycolamide (TODGA) in dodecane is studied using synchrotron small angle X-ray scattering (SAXS) and X-ray absorption fine structure spectroscopy (EXAFS). This system is of technological importance in f-element separation for nuclear fuel cycle applications, where extraction is controlled by varying nitric acid concentration. Extraction is promoted at low and high concentration, butmore » is retarded at intermediate concentration, leading to a U-shaped function; the structural origins of which we investigate. At the nanoscale, the solution is apparently comprised of reverse micelles with polar cores of approximately 1 nm in size, and these remain virtually unchanged as acid concentration is varied. Inside the polar cores, the coordination environment of Eu(III) switches from a 9-coordinate [Eu(TODGA) 3] 3+ motif at high acid, to a 6-coordinate HDEHP-dominated complex resembling Eu(HDEHP·DEHP) 3 at low acid. The results show that extraction is controlled within the coordination sphere, where it is promoted under conditions that favor coordination of either one of the two organic ligands, but is retarded under conditions that encourage mixed complexes. Lastly, our results link solution structure with ion transport properties in a technologically-important liquid-liquid ion extraction system.« less
  • The linear polyether, 1, 13-bis-(8-quinolyl)-1,4,7,10,13-pentaoxatridecane (K-5), has been shown to enhance the extraction of americium (Am(III)), curium (Cm(III)), and europium (Eu(III)) by thenoyltrifluoracetone (hTTA). The extraction of the trivalent metals from an aqueous acetate buffer system (pH = 4.8) into HTTA/chloroform at 25/sup 0/C was studied as a function of the concentration of K-5 in the organic phase. The synergistic specie was determined to be M(TTA)/sub 3/ K-5 and organic phase stability constants for the formation of this complex were evaluated. The results of this study indicate that K-5 has the ability to show some size selectivity for the trivalentmore » metal ion. 3 figures, 3 tables.« less
  • Solvent extraction of Eu(III) and Am(III) from weakly acidic solutions with octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and 2,6-bis((diphenylphosphino)methyl)pyridine N,P,P-trioxide (NOPOPO) in 1,2-dichloroethane was studied on a comparative basis. NOPOPO was found to exhibit unusually high extractability for Eu(III) and Am(III), probably due to its trifunctional nature, sufficient steric flexibility and basicity of the functional groups. Both CMPO and NOPOPO demonstrated synergistic effects in extraction of Eu(III) and Am(III) when used in combination with thenoyltrifluoroacetone (HTTA). However, the stoichiometry of the extracted species with CMPO/HTTA and NOPOPO/HTTA was different under similar experimental conditions. The extractant dependencies of the synergistic extractions suggest that themore » extracted species are the adduct complexes, M(ClO{sub 4})(TTA){sub 2}(CMPO){sub 2} and M(ClO{sub 4}){sub 2}(TTA)(NOPOPO){sub 2}, respectively. It was also observed that CMPO and CMPO/HTTA in dichloroethane extracted Eu(III) and Am(III) equally well, with very similar extraction constants. However, NOPOPO and NOPOPO/HTTA in dichloroethane demonstrated a slight preference for Eu(III) over Am(III), with the extraction constants for Eu(III) more than one order of magnitude higher than that for Am(III).« less