Abstract
A robust solvent suitable for extracting cesium from alkaline nitrate media like that of the high-level liquid waste stored at the U.S. Department of Energy Savannah River Site has been developed. The solvent is composed of the cesium extractant calix[4]arene-bis-(tert-octylbenzo-crown-6) ('BOBCalixC6') at 0.01 M, the modifier 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol ('Cs-7SBT') at 0.50 M, trioctylamine ('TOA') at 0.001 M, and the aliphatic diluent Isopar® L. The solvent holds up exceptionally well under various stresses, such as sustained contact with waste simulant and dilute nitric acid; repeated extraction, scrubbing, and stripping cycles; and excessive loading. The behavior of the solvent in batch-equilibrium flowsheet tests conducted at 15, 25, and 45 °C is presented. Flowsheet calculations show that the Savannah River Site requirements for a decontamination factor of 40,000 and a cesium concentration factor of 12 could be met in a 22-stage bank of 25-cm centrifugal contractors at 25 °C with conservative assumptions regarding hydrodynamics and stage efficiency. Exploiting the temperature dependence of extraction and stripping could reduce the number of stages to 18.
Original language | English |
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Pages (from-to) | 1079-1107 |
Number of pages | 29 |
Journal | Solvent Extraction and Ion Exchange |
Volume | 18 |
Issue number | 6 |
DOIs | |
State | Published - 2000 |
Funding
We thank Jeffrey C. Bryan, Charles F. Coleman, and Frederick V. Sloop, Jr. for internal review of the manuscript. This research was sponsored by the Efficient Separations and Processing Crosscutting Program, Office of Science and Technology, Office of Environmental Management, U. S. Department of Energy, under contract number DE-AC05-000R22725 with Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC.