Synergism and Aggregation in Multi-Extractant Solvent Extraction Systems

ABSTRACT

Several combinations of lipophilic extractants have been studied with the objective of investigating the synergistic behavior of metal ion extraction and its relation to reverse micelle formation. Combinations of acidic and neutral extracting reagents that have displayed synergic behavior in other studies were tested. While most of these either showed limited synergy or no correlation with water uptake under the conditions used here, two of the systems showed extraction synergy. These two extraction systems: 2-bromodecanoic acid with 2,2ʹ:6ʹ,2ʺ-terpyridine; and tributyl phosphine oxide with 2-thenoyltrifluoroacetone were modeled based on two different theoretical approaches: microemulsion-assisted extraction; or the formation of mixed complexes in the organic phase. Comparisons between the two models showed that in the case of bromodecanoic acid and terpyridine the approach of mixed complexes provided a somewhat better fit while the second system was not modeled well with either approach. Further work on the species present in the organic phase is needed to determine the role, if any, of aggregates in synergistic solvent extraction systems.

KEYWORDS:

• Synergistic extraction
• microemulsions
• An/Ln separation
• mixed complexes
• extraction modeling

Acknowledgments

The authors wish to thank the U.S. Department of Energy through the Nuclear Energy University Program, NEUP contract No. 120569 for financial support. The UCI TRIGA® Facility for neutron activation analysis and the UC Irvine Metrohm Lab for help with the IC analysis.

Supplementary material

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Additional information

Funding

This work was supported by the US Department of Energy: [Grant Number NEUP contract No. 120569].