Abstract
A series of novel alkylphenoxy flourinated alcohols were prepared and investigated for their effectiveness as modifiers in solvents containing calix[4]arene-bis-(tert-octylbenzo)-crown-6 for the extraction of cesium from alkaline nitrate media. The structure of the flourinated portion of the modifier influences the chemical stability, and a modifier that contained a terminal 1,1,2,2-tetrafluoroethoxy group was found to decompose following long-term exposure to warm alkaline solutions. However, replacement of the tetrafluoroethoxy group with a 2,2,3,3-tetrafluoropropoxy group led to a series of modifiers that possessed the alkaline stability required for a solvent extraction process. Within this series of modifiers, the structure of the alkyl substituent (tert-octyl, tert-butyl, tert-amyl, and sec-butyl) of the alkylphenoxy moiety was found to have a profound impact on the phase behavior of the solvent in liquid-liquid contacting experiments, and hence on the overall suitability of the modifier for a solvent extraction process. The sec-butyl derivative [1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butyl-phenoxy)-2-propanol] (Cs-7SB) was found to possess the best overall balance of properties with respect to third phase and coalescence behavior, cleanup following degradation, resistance to solids formation, and cesium distribution behavior. Accordingly, this modifier was selected for use as a component of the solvent employed in the Caustic-Side Solvent Extraction (CSSX) process designed for the removal of cesium from high-level nuclear waste (HLW) at the U.S. Department of Energy's (DOE) Savannah River Site. In batch equilibrium experiments, this solvent has also been successfully shown to extract cesium from both simulated and actual solutions generated from caustic leaching of HLW tank sludge stored in tank B-110 at the DOE's Hanford Site.
| Original language | English |
|---|---|
| Pages (from-to) | 141-170 |
| Number of pages | 30 |
| Journal | Solvent Extraction and Ion Exchange |
| Volume | 21 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 2003 |
Funding
The authors wish to thank Dr. Phillip F. Britt (ORNL) for performing GC=MS analyses and Dr. Reid Peterson and colleagues (WSRC) for performing DSC measurements on the Cs-6 hydrate. The authors also thank Dr. Leon Maya for internal review of the manuscript. This research was sponsored by the U.S. Department of Energy, Office of Environmental Management, through (1) the Efficient Separations and Processing (ESP) Crosscutting Program, Office of Science and Technology; and (2) the Office of Project Completion via Westinghouse Savannah River Corporation. Oak Ridge National Laboratory is managed and operated by UT-Battelle, LLC under contract number DE-AC05-00OR22725 with the U.S. Department of Energy. Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle under Contract DE-AC06-76RLO 1830.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | |
| Battelle | DE-AC06-76RLO 1830 |
| Office of Environmental Management | |
| Office for Science and Technology of the Embassy of France in the United States |
Keywords
- CSSX
- Cesium extraction
- Fluorinated alcohol
- Modifier