Hostname: page-component-8448b6f56d-42gr6 Total loading time: 0 Render date: 2024-04-18T22:49:21.926Z Has data issue: false hasContentIssue false
  • English
  • Français

Factors affecting the dissociation of metal ions from humic substances

Published online by Cambridge University Press:  02 January 2018

Nick Bryan ,
Dominic Jones ,
Rose Keepax ,
Dean Farrelly ,
Liam Abrahamsen ,
Rebecca Beard ,
Nigel Li  and
George Weir
Nick Bryan*
Affiliation:
National Nuclear Laboratory, 5th Floor, Chadwick House, Birchwood, Warrington WA3 6AE, UK
Dominic Jones
Affiliation:
Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Manchester M13 9PL, UK
Rose Keepax
Affiliation:
Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Manchester M13 9PL, UK
Dean Farrelly
Affiliation:
Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Manchester M13 9PL, UK
Liam Abrahamsen
Affiliation:
National Nuclear Laboratory, 5th Floor, Chadwick House, Birchwood, Warrington WA3 6AE, UK
Rebecca Beard
Affiliation:
Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Manchester M13 9PL, UK
Nigel Li
Affiliation:
Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Manchester M13 9PL, UK
George Weir
Affiliation:
National Nuclear Laboratory, 5th Floor, Chadwick House, Birchwood, Warrington WA3 6AE, UK
*
*E-mail: nick.bryan@nnl.co.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.

Previously, it has been suggested that metal ions complexed to humic acid in the environment might show slower dissociation than those added to humic substances in the laboratory, which has serious implications for the transport of radionuclides in the environment. The dissociation of lanthanide and anthropogenic actinide ions from humic substance complexes has been studied as a function of humic concentration and metal ion:humic concentration ratio. The results suggest that the apparently slower kinetics observed for metal ions complexed in the environment are probably due to the large humic concentrations that are used in those studies. Further, there is no evidence that the dissociation rate constant varies at very low metal ion concentrations. Although humic samples size-fractionated by ultrafiltration showed that more metal may be bound non-exchangeably, there was no evidence for different rate constants. Ultrafiltration of Eu(III)/humic acid mixtures did show a shift in Eu from smaller to larger fractions over a period of two days. Therefore, the results suggest that dissociation rate constants determined in the laboratory at metal ion concentrations higher than those expected in the environment may be used in predicting radionuclide mobility, provided that the humic acid concentration is in the range expected at the site.

Keywords

dissociationmetal ionshumic substanceslanthanideactinide
Type
Research Article
Information
Mineralogical Magazine , Volume 79 , Issue 6 , November 2015 , pp. 1397 - 1405
Creative Commons
Creative Common License - CCCreative Common License - BY
Copyright © The Mineralogical Society of Great Britain and Ireland 2015. This is an open access article, distributed under the terms of the Creative Commons Attribution (CC BY) license (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 2015

References

Artinger, R., Schuessler, W., Schaefer, T. and Kim, J.I. (2002) A kinetic study of Am(III)/humic colloid interactions. Environmental Science & Technology, 36, 4358–4363.CrossRefGoogle ScholarPubMed
Bryan, N.D., Jones, M.N., Birkett, J. and Livens, F.R. (2001a) The application of a new method of analysis of ultracentrifugation data to the aggregation of a humic acid by cupric ions. Analytica Chimica Acta, 437, 281–289.CrossRefGoogle Scholar
Bryan, N.D., Jones, M.N., Birkett, J. and Livens, F.R. (2001b) Aggregation of humic substances by metal ions measured by ultracentrifugation. Analytica Chimica Acta, 437, 291–308.CrossRefGoogle Scholar
Bryan, N.D., Jones, D.M., Keepax, R.E. and Farelly, D. (2006) Non-exchangeable binding of radionuclides by humic substances: A natural chemical analogue. Pp. 32-37 in: Recent Advances in Actinide Science (I. May, R. Alvarez andN. Bryan, editors), Royal Society of Chemistry, Cambridge, UK.Google Scholar
Bryan, N.D., Jones, D.L.M., Keepax, R.E., Farrelly, D.H., Abrahamsen, L.G., Pitois, A., Ivanov, P., Warwick, P. and Evans, N. (2007) The role of humic non-exchangeable binding in the promotion of metal ion transport in the environment. Journal of Environmental Monitoring, 9, 329–347.Google ScholarPubMed
Conte, P. and Piccolo, A. (1999) Conformational arrangement of dissolved humic substances. Influence of solution composition on association of humic molecules. Environmental Science & Technology, 33, 1682–1690.CrossRefGoogle Scholar
Davis, J.R., Higgo, J.J.W., Noy, D.J. and Hooker, P.J. (2000) Complexation studies of uranium and thorium with a natural fulvic acid. Pp. 85-100 in: Effects of Humic Substances on the Migration of Radionuclides: Complexation and Transport of the Actinides (G. Buckau, editor), Wissenschaftliche Berichte (FZKA 6524, ISSN 0947-8620), Forschungszentrum Karlsruhe Technik und Umwelt, Karlsruhe, Germay.Google Scholar
Geckeis, H., Rabung, T., Manh, T.N., Kim, J.I. and Beck, H.P. (2002) Humic colloid-borne natural polyvalent metal ions: Dissociation experiment. Environmental Science & Technology, 36, 2946–2952.CrossRefGoogle ScholarPubMed
Jones, M.N. and Bryan, N.D. (1998) Colloidal properties of humic substances. Advances in Colloid and Interface Science, 78, 1–48.CrossRefGoogle Scholar
Keepax, R.E., Jones, D.M., Pepper, S. and Bryan, N.D. (2002) The effects of humic substances upon radioactivity in the environment. Pp. 143-177 in: Interactions of Microorganisms with Radionuclides (Keith-Roach, M. and Livens, F.R., editors), Elsevier.Google Scholar
King, S.J., Warwick, P., Hall, A. and Bryan, N.D. (2001) The dissociation kinetics of dissolved metal-humate complexes. Physical Chemistry Chemical Physics, 3, 2080–2085.CrossRefGoogle Scholar
Lippold, H., Eidner, S., Kumke, M. and Lippmann-Pipke, J. (2012) Diffusion, degradation or on-site stabilisation — Identifying causes of kinetic processes involved in metal—humate complexation. Applied Geochemistry, 27, 250–256.CrossRefGoogle Scholar
Livens, F.R. and Singleton, D.L. (1991) Plutonium and americium in soil organic matter. Journal of Environmental Radioactivity, 13, 323–339.CrossRefGoogle Scholar
Monsallie, J., Schuessler, W., Buckau, G., Rabung, T., Kim, J.I., Jones, D., Keepax, R. and Bryan, N. (2003) Kinetic investigation of Eu(III)-humate interactions by ion exchange resins. Analytical Chemistry, 75, 3168–3174.CrossRefGoogle Scholar
Reid, P.M., Wilkinson, A.E., Tipping, E. and Jones, M.N. (1991) Aggregation of humic substances in aqueous media as determined by light-scattering methods. Journal of Soil Science, 42, 259–270.CrossRefGoogle Scholar
Schuessler, W., Artinger, R., Kienzler, B. and Kim, J.I. (2000) Conceptual modeling of the humic colloid-borne americium(III) migration by a kinetic approach. Environmental Science & Technology, 34, 2608–2611.CrossRefGoogle Scholar
Warwick, P.W., Hall, A., Pashley, V., Bryan, N.D. and Griffin, D. (2000) Modelling the effect of humic substances on the transport of europium through porous media: a comparison of equilibrium and equilibrium/kinetic models. Journal of Contaminant Hydrology, 42, 19–34.CrossRefGoogle Scholar