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Supercritical Fluid Extraction: Spectroscopic Study of Interactions - Comparison to Solvent Extraction

Abstract : Supercritical fluid carbon dioxide (SF-CO2) was chosen to study Supercritical Fluid Extraction (SFE) of cesium and uranium. At first, crown ethers were considered as chelating agents for the SFE of cesium. The role of water and its interaction with crown ethers were especially studied using Fourier-Transform Infra-Red (FT-IR) spectroscopy in SF-CO2. A sandwich configuration between two crown ethers and a water molecule was observed in the SF-CO2 phase for the first time. The equilibrium between the single and the bridge configurations was defined. The enthalpy of the hydrogen bond formation was also calculated. These results were then compared to the one in different mixtures of chloroform and carbon tetra-chloride using Nuclear Magnetic Resonance (NMR). To conclude this first part and in order to understand the whole picture of the recovery of cesium, I studied the role of water in the equilibrium between the cesium and the dicyclohexano18-crown-6. In a second part, the supercritical fluid extraction of uranium was studied in SF-CO2. For this purpose, different complexes of TriButyl Phosphate (TBP), nitric acid and water were used as chelating and oxidizing agents. I first used FT-IR to study the TBP-water interaction in SF-CO2. These results were then compared to the one obtained with NMR in chloroform. NMR spectroscopy was also used to understand the TBP-nitric acid-water interaction first alone and then in chloroform. To conclude my research work, I succeeded to improve the efficiency of uranium extraction and stripping into water for a pilot-plant where enriched uranium is extracted from incinerated waste coming from nuclear fuel fabrication. TBP-nitric acid complexes were used in SF-CO2 for the extraction of uranium from ash.
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Contributor : Anne Rustenholtz Farawila <>
Submitted on : Sunday, July 3, 2005 - 2:26:56 PM
Last modification on : Thursday, April 23, 2020 - 2:26:21 PM
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Anne Rustenholtz Farawila. Supercritical Fluid Extraction: Spectroscopic Study of Interactions - Comparison to Solvent Extraction. Other. Université Louis Pasteur - Strasbourg I, 2005. English. ⟨tel-00009652⟩

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