Solution coordination chemistry of uranium - vi - in ternary systems

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Project objective

Research objectives and content The first step in any modeling of the chemistry in complex aquatic systems in nature is an analysis of the total concentrations of components and their chemical speciation. Chemical models are necessary for the understanding of solubility control, sorption and the transport of chemical elements in ground and surface water systems. This proposal deals with the chemistry of uranium(VI) in aqueous sulfate solutions. The focus will be on the formation of ternary complexes. There is very little information on such species, but very good reasons to assume that they are important for speciation. In surface and ground waters were found uranium and sulfate concentrations of about 10-5M and about 3.10-2M (1), respectively. The solution chemistry of this system at sulfate concentrations > O.5M has been investigated by Grenthe and Lagerman (2) using potentiometric methods which provide only provisional information on the chemistry of the system. In the proposed study we will investigate the system at lower sulfate concentrations and also use other experimental techniques such as 17O-NMR (3), EXAFS and TRLFS to improve the equilibrium model. The focus of the proposed study is on the fundamental chemistry of uranium(VI), but the information obtained is highly relevant for the understanding of uranium(VI) in complex aquatic systems in nature. (1) G. Geipel, A. Brachmann, V. Brendler, G. Bernhard, H. Nitsche, Uranium-(VI) Sulfate Complexation Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS). Report FZR-95, Forschungszentrum Rossendorf e.V., Institute of Radiochemistry, Annual Report 1995, p. 5-7. (2) I. Grenthe, B. Lagerman, Radiochim. Acta 61, 169 (1993). (3) Z. Szabo, J. Glaser, I. Grenthe, Inorg. Chem. 35, 2036 (1996). Training content (objective, benefit and expected impact) The group of Prof. I. Grenthe in Stockholm (KTH) has a long experience in solution chemical methodology and have also made extensive investigations of the chemistry of uranium and other actinides. The experimental facilities are excellent with state of the art equipment for potentiometric investigations, NMR, Raman spectroscopy etc. The research team comprises experts in all these areas. The project involves use of a variety of experimental methods which will provide me with a good opportunity to learn new techniques and their theory. The group of Prof. H. Nitsche in Rossendorf (FZR) has much experience in the methodology of TRLFS. The laser equipment is excellent. The project will involve use of this experimental method as a cooperation between these two european research institutes.

Original text from CORDIS.

Participants

• ROYAL INSTITUTE OF TECHNOLOGY · STOCKHOLMCoordinatorSweden
• Not availableCity levelGermany

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