Conditional stability parameters for the actinides (IV)-humic acid system: a search for consistency - Archive ouverte HAL Access content directly
Journal Articles Radiochimica Acta Year : 2008

Conditional stability parameters for the actinides (IV)-humic acid system: a search for consistency

(1) , (2) , (3)
1
2
3

Abstract

The coherence of actinide(IV) complexation by humic substances (HS) is reviewed and new data are proposed. In a first attempt, the values of independent data from literature on Th(IV), U(IV), and Pu(IV) are collected, selected, and compiled. The data obtained follow the “classical” trend of increasing conditional formation “constants” with pH, led both by the increasing ionisation of HS and by the extensive hydrolysis of the tetravalent actinides. Even though a fair agreement is evident, the experimental uncertainties do not permit a full analogy between the actinides(IV) to be ascertained. In a second attempt, the experiments from which the original data are available were reinterpreted using only one hydrolysis constant set for U(IV) as an example, considering that all actinides(IV) have analogous humic complexation behaviour. Hence, the obtained evolution of conditional formation “constants” is much more coherent and the uncertainties do not permit to distinguish an actinide(IV) from one another. The obtained data are then applied to independent laboratory and in situ experiments in order to delimit the domain of possible applicability. This exercise demonstrates the treatment of data through analogy in the case of actinides(IV) and would permit to limit and orientate the number of necessary, but difficult, experiment with redox sensitive elements like U, Np, or Pu. It also demonstrates that complexation-only mechanisms may not be sufficient to understand field observations.
Fichier principal
Vignette du fichier
Reiller_RCA_96_345.pdf (296.26 Ko) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

cea-00285033 , version 1 (18-08-2008)

Identifiers

Cite

Pascal E. Reiller, Nick Evans, Gyula Szabo. Conditional stability parameters for the actinides (IV)-humic acid system: a search for consistency. Radiochimica Acta, 2008, 96 (6), pp.345-358. ⟨10.1524/ract.2008.1500⟩. ⟨cea-00285033⟩

Collections

CEA DEN DEN-SACLAY
125 View
280 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More