Gent 2005 8 page paper Final version.pdf (321.67 kB)
Studies on metal gluconic acid complexes
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posted on 2008-02-04, 17:21 authored by Peter Warwick, Nick Evans, Sarah VinesThe presence of organic complexants, such as gluconic acid, in an intermediate-level
radioactive-waste (ILW) repository may have a detrimental effect on the sorption of
radionuclides, by forming organic complexes in solution. In order to assess this, stability
constants are required for the complexes formed with radionuclides at high pH. This study
reports the stability constants for the reactions of metals with gluconic acid (Gl). The metals
studied were Cd, Ce, Co, Eu, Fe(II), Fe(III), Ho and U(VI) at pH 13.3; and Ce, Co and U(VI) at
pH 7. The constants were measured by the Schubert (ion-exchange) or solubility product
methods. Stoichiometries of the complexes were also determined. At pH 7 each complex was of
the form M1Gl1, with log β values suggestive of salt formation. The M2+ log β values were
between 13 and 20. For M3+, there was less consistency. The M2Gl1 complexes (Ho & Ce) had
values of 49.8 and 43.9, whereas the M1Gl1 type (Fe(III) & Eu) range from 24 to 38. The
constants have enabled speciation calculations to be performed showing the effect of gluconic
acid on the metal’s solubility. Solubility is predicted to increase in the presence of gluconic acid
from pH 9 to 13.5, suggesting that gluconic acid may have an impact on radionuclide behaviour.
The largest increases in solubility are for Cd, Co, Eu, Ho and Ni, the smallest is with U(VI).
History
School
- Science
Department
- Chemistry
Citation
WARWICK, P., EVANS, N. and VINES, S., 2006. Studies on metal gluconic acid complexes. IN: Isheghem, Van P. (ed.). Scientific Basis for Nuclear Waste Management XXIX (Materials Resource Society Symposium Proceedings, 932, Warrendale, PA), pp. 959-966Publisher
© Materials Resource SocietyPublication date
2006Notes
This is a conference paper. The definitive version is available at: http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=6834&DID=176959Language
- en