Separation of cesium from high ionic strength solutions using a cobalt hexacyanoferrate-modified graphite electrode
- Univ. of Washington, Seattle, WA (United States). Dept. of Civil and Environmental Engineering
The composition of the Hanford and many other tank wastes varies from tank to tank, but in all cases almost 99% of their radioactivity is caused by Cs[sup 137] and Sr[sup 90]. These radionuclides comprise an infinitesimally small volume or mass fraction of wastes, and their separation from nontoxic salts will dramatically ease the handling of the wastes. Graphite electrodes modified with cobalt hexacyanoferrate (CoHCF) were used to investigate the feasibility of electrochemically (EC) controlled ion exchange for separation and transfer of Cs from high sodium wastes. A thin layer of CoHCF was formed on the graphite substrate. The surface CoHCF phase was highly selective to Cs[sup +] in the presence of overwhelmingly higher concentrations of Na[sup +] and K[sup +]. Cs[sup +] was incorporated into the electrode at 0 V and expelled at +1.0 V. X-ray photoelectron spectroscopy (XPS) confirmed the EC control of the cesium flux and its association with the Fe oxidation state in the CoHCF phase. There was a good correlation between the electric charge passed through the electrode and the amount of Cs incorporated or released. The maximum share of charge associated with Cs[sup +] incorporation is ca. 40%. The performance of the electrode was stable in the range of pH from 1 to 11, but it deteriorated at pH > 11. The CoHCF electrodes performed well in multicycle processes of Cs separation and transfer, but the impact on non-EC-controlled cation exchange and carryover by the porous substrate were also significant.
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG07-96ER62313
- OSTI ID:
- 6192477
- Journal Information:
- Environmental Science and Technology, Vol. 33:15; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CESIUM 137
ELECTROCHEMISTRY
ION EXCHANGE
PERFORMANCE
SEPARATION PROCESSES
WASTE PROCESSING
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CESIUM ISOTOPES
CHEMISTRY
INTERMEDIATE MASS NUCLEI
ISOTOPES
MANAGEMENT
NUCLEI
ODD-EVEN NUCLEI
PROCESSING
RADIOISOTOPES
WASTE MANAGEMENT
YEARS LIVING RADIOISOTOPES
052001* - Nuclear Fuels- Waste Processing