Hostname: page-component-7479d7b7d-rvbq7 Total loading time: 0 Render date: 2024-07-10T23:15:23.125Z Has data issue: false hasContentIssue false
  • English
  • Français

The complexation of Tc(IV) with EDTA and picolinic acid at high pH

Published online by Cambridge University Press:  05 July 2018

N. D. M. Evans  and
R. Hallam
N. D. M. Evans*
Affiliation:
Department of Chemistry, Loughborough University, Loughborough LE11 3TU, UK
R. Hallam
Affiliation:
Department of Chemistry, Loughborough University, Loughborough LE11 3TU, UK
*
*E-mail: n.d.m.evans@lboro.ac.uk
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In the UK, technetium may be disposed of in a high pH, low Eh cementitious repository. In such a scenario, its chemistry would be dominated by TcO4−, in aerobic conditions and the sparingly soluble TcO2(s) in anaerobic conditions. Repository heterogeneity could mean that both Tc(VII) and Tc(IV) are present simultaneously. The anthropogenic ligands EDTA and picolinic acid are commonly used as decontamination agents and are likely to be present in intermediate-level waste (ILW). They could complex with Tc(IV) increasing its aqueous concentration and mobility in the cement porewaters and beyond. The conditional stability constants (measured in 0.3 mol dm−3 NaOH) for the Tc(IV)–EDTA and Tc(IV)–picolinic acid complexes have been determined to be: βTc(IV)−EDTA = 1.6 × 1026, which corresponds to log β = 25.2±0.6; and βTc(IV)−PA = 8.65 × 1026, which corresponds to log β = 26.9±0.1, respectively.

Keywords

complexation modellingedtaengineered barrier systempicolinic acidradionuclide transporttechnetium
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 8 , December 2012 , pp. 3435 - 3438
Creative Commons
Creative Common License - CCCreative Common License - BY
© [2012] The Mineralogical Society of Great Britain and Ireland. This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY) licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

References

Copplestone, D., Jackson, D., Hartnoll, R., Johnson, M., McDonald, P. and Wood, N. (2004) Seasonal variations in activity concentrations of Tc-99 and Cs-137 in the edible meat fraction of crabs and lobsters from the central Irish Sea. Journal of Environmental Radioactivity, 3, 29–48.CrossRefGoogle Scholar
Cui, D. and Eriksen, T.E. (1996) Reduction of pertechnetate by ferrous iron in solution: influence of sorbed and precipitated Fe(II). Environmental Science and Technology, 30, 2259–2262.CrossRefGoogle Scholar
Gorski, B. and Koch, H. (1969) Zur Chemie des Technetium in wäßriger Lösung - I. U¨ ber den Zustand des vierwertigen Technetium in wäßriger Lösung. Journal of Inorganic and Nuclear Chemistry, 31, 3565–3571.CrossRefGoogle Scholar
Gorski, B. and Koch, H. (1970) U¨ ber die Komplexbildung von Technetium mit chelatbildenden Liganden - II. Journal of Inorganic and Nuclear Chemistry, 32, 3831–3836.CrossRefGoogle Scholar
Hummel, W., Anderegg, G., Rao, L., Puigdomenech, I. and Tochiyama , O. (2005) Chemi c a l Thermodynamics of Compounds and Complexes of U, Np, Pu, Am, Tc, Se, Ni and Zr with Selected Organic Ligands. Elsevier, Amsterdam.Google Scholar
Maes, A., De Brabandere, J. and Cremers, A. (1988) Modified Schubert method for the measurement of the stability of europium humic acid complexes in alkaline conditions. Radiochimica Acta, 44/45, 51–56.Google Scholar
Warwick, P., Evans, N., Hall, A. and Vines, S. (2003) Complexation of Ni(II) by a-isosaccharinic acid and gluconic acid from pH 7 to pH 13. Radiochimica Acta, 91, 233–240.Google Scholar
Warwick, P., Evans, N., Hall, A. and Vines, S. (2004) Stability constants of uranium (IV)-a-isosaccharinic and gluconic acid complexes. Radiochimica Acta, 92, 1–6 CrossRefGoogle Scholar
Warwick, P., Aldridge, S., Evans, N. and Vines, S. (2007) The solubility of technetium(IV) at high pH. Radiochimica Acta, 95, 709–716.Google Scholar