1. Kinetic study of uranium speciation in model solutions and in natural waters using Competitive Ligand Exchange Method
- Author
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Jiujiang Zhao, Chuni L. Chakrabarti, Ismail I. Fasfous, Sheren Boca, John Murimboh, Parthasarathi Chakraborty, and Tahir Yapici
- Subjects
inorganic chemicals ,Inorganic chemistry ,Kinetics ,chemistry.chemical_element ,Ligands ,Mass spectrometry ,complex mixtures ,Dissociation (chemistry) ,Analytical Chemistry ,chemistry.chemical_compound ,Humic acid ,Water pollution ,Inductively coupled plasma mass spectrometry ,chemistry.chemical_classification ,technology, industry, and agriculture ,Water ,Hydrogen-Ion Concentration ,Uranium ,Carbon ,Solutions ,Models, Chemical ,chemistry ,Environmental chemistry ,Carbonate - Abstract
Kinetic speciation of uranium in model solutions containing uranium and humic acid (HA) and in natural waters has been investigated by Competitive Ligand Exchange Method (CLEM). In alkaline freshwaters, most of uranium species were uranium–carbonate species, which were labile in the CLEM experiment. The uranium speciation of every sample was characterized either as “labile” or “non-labile” uranium complexes depending on the dissociation rate coefficients of the complexes. The results showed that as the U(VI)/HA ratio was decreased, the dissociation rate coefficients decreased and the labile fraction decreased as well. When the U(VI)/HA ratio was 0.1, the labile fraction of the U(VI)-HA increased with increasing pH; however, there was no pH effect on the dissociation of U(VI)-HA complexes at lower U(VI)/HA ratios. Chelex-100 had some limitations in its use for the study of dissociation of U(VI)-HA complex at very low U(VI)/HA ratios. By developing an analytical method and procedure for quantitative determination of kinetic parameters for the dissociation of uranium-HA complexes in model solutions and natural waters, this work has made a substantial contribution to analytical chemistry.
- Published
- 2009
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