Fundamental studies and potential applications of cloud point extraction

Separation of the components of nuclear fuel provides an interesting and complicated separation challenge as the trivalent lanthanides and actinides must be separated from each other. The difficulties of this separation have prompted exploration of novel separation techniques, such as cloud point extraction (CPE). CPE is an aqueous separation technique that utilizes a surfactant, in place of an organic solvent, for phase separation. The technique has shown utility for transition metal separations and some applicability to lanthanide separation. While numerous separation schemes have been demonstrated with CPE, very little fundamental research has been done to expand understanding of the mechanism of extraction and phase separation in the system. Current CPE systems have been developed using a "trial and error" approach with no insight into how to improve the separation.;The focus of this dissertation was to develop a better fundamental understanding of the mechanism of extraction in CPE systems, as a means of improving separation system design. To achieve this goal a CPE system for lanthanide and actinide separation was designed and studied. The influence of electrolytes on the extraction behavior and system behavior was examined along with the influence of the surfactant on metal ligand complexation using radiometric techniques, potentiometric titrations, uv-visible spectroscopy, and fluorescence spectroscopy. These studies combined to help give insight into a seemingly simple extraction system, showing CPE is in fact much more complicated than initially expected. The goal of these studies was to provide a better understanding of the CPE system to facilitate improved system design.