Jump to ContentJump to Main Navigation
Show Summary Details
More options …

Radiochimica Acta

International Journal for chemical aspects of nuclear science and technology

Editor-in-Chief: Qaim, Syed M.

IMPACT FACTOR 2018: 1.339

CiteScore 2018: 1.20

SCImago Journal Rank (SJR) 2018: 0.333
Source Normalized Impact per Paper (SNIP) 2018: 0.720

See all formats and pricing
More options …
Volume 107, Issue 7


Determination of complex formation constants of neptunium(V) with propionate and lactate in 0.5–2.6 m NaCl solutions at 22–60°C using a solvent extraction technique

Aleksandr N. Vasiliev
  • Karlsruher Institut für Technologie (KIT), Institut für Nukleare Entsorgung, P.O. Box 3640, 76021 Karlsruhe, Germany
  • Radiochemistry Division, Chemistry Department, Lomonosov Moscow State University, Moscow 119992, Russia
  • Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312, Russia
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Nidhu L. Banik
  • Karlsruher Institut für Technologie (KIT), Institut für Nukleare Entsorgung, P.O. Box 3640, 76021 Karlsruhe, Germany
  • JRC-KARLSRUHE, G.II.6 – Nuclear Safeguards and Forensics, European Commission, P.O. Box 2340, D-76125 Karlsruhe, Germany
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Rémi Marsac
  • Karlsruher Institut für Technologie (KIT), Institut für Nukleare Entsorgung, P.O. Box 3640, 76021 Karlsruhe, Germany
  • Univ Rennes, CNRS, Géosciences Rennes – UMR 6118, F-35000 Rennes, France
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Stepan N. Kalmykov
  • Radiochemistry Division, Chemistry Department, Lomonosov Moscow State University, Moscow 119992, Russia
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Christian M. Marquardt
  • Corresponding author
  • Karlsruher Institut für Technologie (KIT), Institut für Nukleare Entsorgung, P.O. Box 3640, 76021 Karlsruhe, Germany, Phone: +49 721 60825686
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2019-05-21 | DOI: https://doi.org/10.1515/ract-2019-3107


Natural clay rocks like Opalinus (OPA) and Callovo-Oxfordian (COx) clay rock are considered as potential host rocks for deep geological disposal of nuclear waste. However, small organic molecules such as propionate and lactate exist in clay rock pore water and might enhance Np mobility through a complexation process. Therefore, reliable complex formation data are required in the frame of the Safety Case for a nuclear waste repository. A solvent extraction technique was applied for the determination of NpO2+ complexation with propionate and lactate. Extraction was conducted from isoamyl alcohol solution containing 10−3 M TTA and 5 · 10−4 M 1,10-phenanthroline. Experiments were performed in 0.5–2.6 m NaCl solutions at temperatures ranging from 22 to 60 °C. Formation of 1:1 Np(V) complexes for propionate and lactate was found under the studied conditions. The SIT approach was applied to calculate equilibrium constants β°(T) at zero ionic strength from the experimental data. Log β°(T) is found linearly correlated to 1/T for propionate and lactate, evidencing that heat capacity change is near 0. Molal reaction enthalpy and entropy (ΔrHm and ΔrSm) could therefore be derived from the integrated van’t Hoff equation. Data for log β° (298.15 K) are in agreement with literature values for propionate and lactate. Np(V) speciation was calculated for concentrations of acetate, propionate and lactate measured in clay pore waters of COx. In addition, the two site protolysis non-electrostatic surface complexation and cation exchange (2SPNE SC/CE) model was applied to quantitatively describe the influence of Np(V) complexation on its uptake on Na-illite, a relevant clay mineral of OPA and COx.

Keywords: Np(V); complexation; complex formation constant; lactate; propionate; solvent extraction

Dedicated to: The memory of Professor Günter Herrmann.


  • 1.

    Kim, J. I.: Chemical behaviour of transuranic elements in natural aquatic systems, In: A. J. Freeman (Ed.), Handbook on the Physics and Chemistry of the Actinides (1986), Elsevier Science Publishers, B. V., Amsterdam, p. 413.Google Scholar

  • 2.

    Choppin, G. R., Rao, L. F.: Complexation of pentavalent and hexavalent actinides by fluoride. Radiochim. Acta 37, 143 (1984).Google Scholar

  • 3.

    Forbes, T. Z., Wallace, C., Burns, P. C.: Neptunyl compounds: polyhedron geometries, bond-valence parameters, and structural hierarchy. Can. Mineral. 46, 1623 (2008).Web of ScienceCrossrefGoogle Scholar

  • 4.

    ONDRAF/NIRAS, SAFIR 2: Safety assessment and feasibility interim report, NIROND-2001-06 E, ONDRAF/NIRAS, Brussels/Belgium (2001).Google Scholar

  • 5.

    OECD: Safety of geological disposal of high-level and longlived radioactive waste in France – an international peer review of the “Dossier 2005 Argile” concerning disposal in the Callovo-Oxfordian formation, NEA No. 6178, OECD Organization for economic cooperation and development (2006).Google Scholar

  • 6.

    Hoth, P., Wirth, H., Reinhold, K., Bräuer, V., Krull, P., Feldrappe, H.: Endlagerung radioaktiver Abfälle in tiefen geologischen Formationen Deutschlands – Untersuchung und Bewertung von Tongesteinsformationen, BGR Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover/Germany (2007).Google Scholar

  • 7.

    Courdouan, A., Christl, I., Meylan, S., Wersin, P., Kretzschmar, R.: Isolation and characterization of dissolved organic matter from the Callovo–Oxfordian formation. Appl. Geochem. 22, 1537 (2007).Web of ScienceCrossrefGoogle Scholar

  • 8.

    Courdouan, A., Christl, I., Meylan, S., Wersin, P., Kretzschmar, R.: Characterization of dissolved organic matter in anoxic rock extracts and in situ pore water of the Opalinus Clay. Appl. Geochem. 22, 2926 (2007).CrossrefWeb of ScienceGoogle Scholar

  • 9.

    Geological disposal of radioactive waste: technological implications for retrievability, IAEA nuclear energy series, NW-T-1.19, ISSN 1995-7807, International Atomic Energy Agency, Vienna, Austria (2009).Google Scholar

  • 10.

    Askarieh, M. M., Hansford, M. I., Staunton, S., Rees, L. V. C.: Complexation of Np (V) in aqueous solutions (No. DOE-HMIP-RR-92.018). Department of the Environment, London, UK (1992).Google Scholar

  • 11.

    Vasiliev, A. N., Banik, N. L., Marsac, R., Froehlich, D. R., Rothe, J., Kalmykov, S. N., Marquardt, C. M.: Np(V) complexation with propionate in 0.5–4 M NaCl solutions at 20–85 °C. Dalton Trans. 44, 3837 (2015).CrossrefPubMedWeb of ScienceGoogle Scholar

  • 12.

    Moore, R. C., Borkowski, M., Bronikowski, M. G., Chen, J., Pokrovsky, O. S., Xia, Y., Choppin, G. R.: Thermodynamic modeling of actinide complexation with acetate and lactate at high ionic strength. J. Sol. Chem. 28, 521 (1999).CrossrefGoogle Scholar

  • 13.

    Tochiyama, O., Inoue, Y., Narita, S.: Complex formation of Np(V) with various carboxylates. Radiochim. Acta 58, 129 (1992).Google Scholar

  • 14.

    Eberle, S. H., Schaefer, J. B.: Stabilitätskonstanten der Komplexe des Neptunyl(V)-lons mit α-Hydroxykarbonsäuren. J. Inorg. Nucl. Chem. 31, 1523 (1969).CrossrefGoogle Scholar

  • 15.

    Carbonaro, R. F., Di Toro, D. M.: Linear free energy relationships for metal-ligand complexation. Geochim. Cosmochim. Acta 71, 3958 (2007).CrossrefGoogle Scholar

  • 16.

    Claret, F., Schaefer, T., Rabung, T., Wolf, M., Bauer, A., Buckau, G.: Differences in properties and Cm(III) complexation behavior of isolated humic and fulvic acid derived from Opalinus clay and Callovo-Oxfordian argillite. Appl. Geochem. 20, 1158 (2005).CrossrefGoogle Scholar

  • 17.

    Sjoblom, R., Hindman, J. C.: Spectrophotometry of neptunium in perchloric acid solutions. J. Am. Chem. Soc. 73, 1744 (1951).CrossrefGoogle Scholar

  • 18.

    Marsac, R., Banik, N. L., Lützenkirchen, J., Marquardt, C. M., Dardenne, K., Schild, D., Rothe, J., Diascorn, A., Kupcik, T., Schäfer, T., Geckeis, H.: Neptunium redox speciation at the illite surface. Geochim. Cosmochim. Acta 152, 39 (2015).Web of ScienceCrossrefGoogle Scholar

  • 19.

    Inoue, Y., Tochiyama, O.: Solvent extraction of neptunium(V) by thenoyltrifluoroacetone and 1,10-phenanthroline or tri-n-octylphosphine oxide. Radiochim. Acta 31, 193 (1982).Google Scholar

  • 20.

    Choppin, G. R., Chen, J.-F.: Complexation of Am(III) by oxalate in NaClO4 media. Radiochim. Acta 74, 105 (1996).Google Scholar

  • 21.

    Choppin, G. R., Erten, H. N., Xia Y.-X.: Variation of stability constants of thorium citrate complexes with ionic strength. Radiochim. Acta 74, 123 (1996).Google Scholar

  • 22.

    Rao, L., Srinivasan, T. G., Garnov, A. Y., Zanonato, P., Di Bernardo, P., Bismondo, A.: Hydrolysis of neptunium(V) at variable temperatures (10–85 °C). Geochim. Cosmochim. Acta 68, 4821 (2004).CrossrefGoogle Scholar

  • 23.

    Maya, L.: Hydrolysis and carbonate complexation of dioxoneptunium(V) in 1.0 M NaClO4 at 25 °C. Inorg. Chem. 22, 2093 (1983).CrossrefGoogle Scholar

  • 24.

    Wruck, D. A., Palmer, C. E. A., Silva, R. J.: A study of americium(III) carbonate complexation at elevated temperatures by pulsed laser photoacoustic spectroscopy. Radiochim. Acta 85, 21 (1999).Google Scholar

  • 25.

    Götz, C., Geipel, G., Bernhard, G.: The influence of the temperature on the carbonate complexation of uranium(VI) – a spectroscopic study. J. Radioanal. Nucl. Chem. 287, 961 (2011).Web of ScienceCrossrefGoogle Scholar

  • 26.

    Altmaier, M., Metz, V., Neck, V., Müller, R., Fanghänel, T.: Solid-liquid equilibria of Mg(OH)2(cr) and Mg2(OH)3Cl·4H2O(cr) in the system Mg-Na-H-OH-Cl-H2O at 25 °C. Geochim. Cosmochim. Acta 67, 3595 (2003).CrossrefGoogle Scholar

  • 27.

    Good, N. E., Winget, G. D., Winter, W., Connolly, T. N., Izawa, S., Singh, R. M.: Hydrogen ion buffers for biological research. Biochemistry 5, 467 (1966).PubMedCrossrefGoogle Scholar

  • 28.

    Zolotov, Y. A., Alimarin, I. P.: Investigation of the chemistry of pentavalent neptunium. J. Inorg. Nucl. Chem. 25, 691 (1963).CrossrefGoogle Scholar

  • 29.

    Rao, L., Tian, G., Srinivasan, T. G., Zanonato, P., Di Bernardo, P.: Spectrophotometric and calorimetric studies of Np(V) complexation with acetate at various temperatures from T=283 to 343 K. J. Sol. Chem. 39, 1888 (2010).CrossrefGoogle Scholar

  • 30.

    Bromley, L. A.: Thermodynamic properties of strong electrolytes in aqueous solutions. AIChE J. 19, 313 (1973).CrossrefGoogle Scholar

  • 31.

    Guillaumont, R., Fanghänel, T., Fuger, J., Grenthe, I., Neck, V., Palmer, D. A., Rand, M. H.: Chemical thermodynamics Vol. 5. Update on the chemical thermodynamics of uranium, neptunium, plutonium, americium and technetium. OECD, NEA-TDB, North Holland, Amsterdam (2003).Google Scholar

  • 32.

    Tian, G., Martin, L. R., Rao, L.: Complexation of lactate with neodymium(III) and europium(III) at variable temperatures. Inorg. Chem. 49, 10598 (2010).PubMedWeb of ScienceCrossrefGoogle Scholar

  • 33.

    Choppin, G. R.: Inner vs outer sphere complexation of f-elements. J. Alloys Compd. 249, 9 (1997).CrossrefGoogle Scholar

  • 34.

    Neck, V., Fanghänel, Th., Rudolph, K., Kim, J. I.: Thermodynamics of neptunium(V) in concentrated salt solutions: chloride complexation and ion interaction (Pitzer) parameters for the NpO2 ion. Radiochim. Acta 69, 39 (1995).Google Scholar

  • 35.

    Froehlich, D. R., Skerencak-Frech, A., Morkos, M.-L. K., Panak, P. J.: A spectroscopic study of Cm (III) complexation with propionate in saline solutions at variable temperatures. New J. Chem. 37, 1520 (2013).Web of ScienceCrossrefGoogle Scholar

  • 36.

    Silva, R. J., Bidoglio, G., Rand, M. H., Robouch, P., Wanner, H., Puigdomenech, I.: Chemical thermodynamics Vol. 2, Chemical thermodynamics of americium. OECD, NEA-TDB, North Holland, Amsterdam (1995).Google Scholar

  • 37.

    Jiang, J., Rao, L., Di Bernardo, P., Zanonato, P. L., Bismondo, A.: Complexation of uranium(VI) with acetate at variable temperatures. J. Chem. Soc. Dalton Trans. 8, 1832 (2002).Google Scholar

  • 38.

    Ahrland, S.: How to distinguish between inner and outer sphere complexes in aqueous solution. Thermodynamic and other criteria. Coord. Chem. Rev. 8, 21 (1972).CrossrefGoogle Scholar

  • 39.

    Fröhlich, D. R., Skerencak-Frech, A., Kaplan, U., Koke, C., Rossberg, A., Panak, P. J.: An EXAFS spectroscopic study of Am(III) complexation with lactate. J. Synchrotron. Radiat. 22, 1469 (2015).CrossrefPubMedWeb of ScienceGoogle Scholar

  • 40.

    Barkleit, A., Kretzschmar, J., Tsushima, S., Acker, M.: Americium(III) and europium(III) complex formation with lactate at elevated temperatures studied by spectroscopy. Dalton Trans. 43, 11221 (2014).Web of SciencePubMedCrossrefGoogle Scholar

  • 41.

    Choppin, G. R., Friedman, Jr. H. G.: Complexes of trivalent lanthanide ions. III. Bidentate chelates. Inorg. Chem. 5, 1599 (1966).CrossrefGoogle Scholar

  • 42.

    Parkhurst, D. L., Appelo, C. A. J.: User’s guide to PHREEQC (Version 2) – a computer program for speciation, batch reaction, one-dimensional transport and inverse geochemical calculation. Water-resources Investigation Report, 99-4259, USGS, Denver, Colorado (1999).Google Scholar

  • 43.

    Bradbury, M. H., Baeyens, B.: Predictive sorption modelling of Ni(II), Co(II), Eu(IIII), Th(IV) and U(VI) on MX-80 bentonite and Opalinus clay, a “bottom-up” approach. Appl. Clay Sci. 52, 2 (2011).Web of ScienceGoogle Scholar

  • 44.

    Marsac, R., Banik, N. L., Lützenkirchen, J., Catrouillet, C., Marquardt, C. M., Johannesson, K. H.: Modeling metal ion-humic substances complexation in highly saline conditions. Appl. Geochem. 79, 52 (2017).Web of ScienceCrossrefGoogle Scholar

  • 45.

    Marsac, R., Banik, N. L., Lützenkirchen, J., Diascorn, A., Bender, K., Marquardt, C. M., Geckeis, H.: Sorption and redox speciation of plutonium on illite under saline conditions. J. Colloid Interface Sci. 485, 59 (2017).Web of SciencePubMedCrossrefGoogle Scholar

  • 46.

    Banik, N. L., Marsac, R., Lützenkirchen, J., Marquardt, C. M., Dardenne, K., Rothe, J., Bender, K., Geckeis, H.: Neptunium sorption and redox speciation at the illite surface under highly saline conditions. Geochim. Cosmochim. Acta 215, 421 (2017).CrossrefWeb of ScienceGoogle Scholar

  • 47.

    Bradbury, M. H., Baeyens, B.: Sorption modeling on illite. Part II: Actinide sorption and linear free energy relationships. Geochim. Cosmochim. Acta 73, 1004 (2009).CrossrefGoogle Scholar

  • 48.

    Gaines, G. I., Thomas, H. C.: Adsorption studies on clay minerals. II. A formulation of the thermodynamics of exchange adsorption. J. Phys. Chem. 21, 714 (1953).CrossrefGoogle Scholar

  • 49.

    Bradbury, M. H., Baeyens, B.: Sorption modeling on illite. Part I: titration measurements and the sorption of Ni, Co, Eu and Sn. Geochim. Cosmochim. Acta 73, 990 (2009).CrossrefGoogle Scholar

  • 50.

    Fröhlich, D. R., Amayri, S., Drebert, J., Reich, T.: Influence of temperature and background electrolyte on the sorption of neptunium(V) on Opalinus clay. Appl. Clay Sci. 69, 43 (2012).CrossrefWeb of ScienceGoogle Scholar

About the article

Received: 2019-01-17

Accepted: 2019-04-01

Published Online: 2019-05-21

Published in Print: 2019-07-26

Citation Information: Radiochimica Acta, Volume 107, Issue 7, Pages 623–634, ISSN (Online) 2193-3405, ISSN (Print) 0033-8230, DOI: https://doi.org/10.1515/ract-2019-3107.

Export Citation

©2019 Walter de Gruyter GmbH, Berlin/Boston.Get Permission

Comments (0)

Please log in or register to comment.
Log in