Details
| Original language | English |
|---|---|
| Pages (from-to) | 547-558 |
| Number of pages | 12 |
| Journal | Radiochimica Acta |
| Volume | 97 |
| Issue number | 10 |
| Publication status | Published - 5 Nov 2009 |
| Externally published | Yes |
Abstract
Safety assessment of nuclear waste disposal includes determination of the possible impact of natural dissolved organic matter on the transport of actinide ions via groundwater into the biosphere. Thereby, much attention is paid to americium as it dominates the radiotoxicity of the nuclear waste after about 300 y and up to about 1000 y (spent fuel) or 100 000 y (vitrified reprocessing waste). A trustworthy description of the influence benefits from a sound chemical process understanding of the americium humate complexation and transport processes. A problem in this respect is that studies by TRLFS lead to inconclusive results with respect to the nature of the complexes involved. In the present study the outcome of TRLFS measurements in H2O and D 2O, and at room temperature and in liquid nitrogen are compared. It is shown that the Cm3+ ion interchanges between aquo ion (Cm aq3+) and humate complex (CmHA) on a time scale of milliseconds in a pH range between 3 and 5.5. Taking this interchange into account, the process can be described in the absence of ternary complexes by the 1:1 stoichiometry formation of one curium humate complex, or a sufficiently narrow distribution of complexes to be represented by one average complex.
Keywords
- Curium, Humic substances, Time resolved laser fluorescence, Trlfs
ASJC Scopus subject areas
- Chemistry(all)
- Physical and Theoretical Chemistry
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In: Radiochimica Acta, Vol. 97, No. 10, 05.11.2009, p. 547-558.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Formation of Cm humate complexes in aqueous solution at pHc 3 to 5.5
T2 - The role of fast interchange
AU - Freyer, M.
AU - Walther, Clemens
AU - Stumpf, Thorsten
AU - Buckau, G.
AU - Fanghänel, Thomas
PY - 2009/11/5
Y1 - 2009/11/5
N2 - Safety assessment of nuclear waste disposal includes determination of the possible impact of natural dissolved organic matter on the transport of actinide ions via groundwater into the biosphere. Thereby, much attention is paid to americium as it dominates the radiotoxicity of the nuclear waste after about 300 y and up to about 1000 y (spent fuel) or 100 000 y (vitrified reprocessing waste). A trustworthy description of the influence benefits from a sound chemical process understanding of the americium humate complexation and transport processes. A problem in this respect is that studies by TRLFS lead to inconclusive results with respect to the nature of the complexes involved. In the present study the outcome of TRLFS measurements in H2O and D 2O, and at room temperature and in liquid nitrogen are compared. It is shown that the Cm3+ ion interchanges between aquo ion (Cm aq3+) and humate complex (CmHA) on a time scale of milliseconds in a pH range between 3 and 5.5. Taking this interchange into account, the process can be described in the absence of ternary complexes by the 1:1 stoichiometry formation of one curium humate complex, or a sufficiently narrow distribution of complexes to be represented by one average complex.
AB - Safety assessment of nuclear waste disposal includes determination of the possible impact of natural dissolved organic matter on the transport of actinide ions via groundwater into the biosphere. Thereby, much attention is paid to americium as it dominates the radiotoxicity of the nuclear waste after about 300 y and up to about 1000 y (spent fuel) or 100 000 y (vitrified reprocessing waste). A trustworthy description of the influence benefits from a sound chemical process understanding of the americium humate complexation and transport processes. A problem in this respect is that studies by TRLFS lead to inconclusive results with respect to the nature of the complexes involved. In the present study the outcome of TRLFS measurements in H2O and D 2O, and at room temperature and in liquid nitrogen are compared. It is shown that the Cm3+ ion interchanges between aquo ion (Cm aq3+) and humate complex (CmHA) on a time scale of milliseconds in a pH range between 3 and 5.5. Taking this interchange into account, the process can be described in the absence of ternary complexes by the 1:1 stoichiometry formation of one curium humate complex, or a sufficiently narrow distribution of complexes to be represented by one average complex.
KW - Curium
KW - Humic substances
KW - Time resolved laser fluorescence
KW - Trlfs
UR - http://www.scopus.com/inward/record.url?scp=70350536186&partnerID=8YFLogxK
U2 - 10.1524/ract.2009.1628
DO - 10.1524/ract.2009.1628
M3 - Article
AN - SCOPUS:70350536186
VL - 97
SP - 547
EP - 558
JO - Radiochimica Acta
JF - Radiochimica Acta
SN - 0033-8230
IS - 10
ER -