Technetium behavior in sulfide and ferrous iron solutions
Pertechnetate oxyanion (/sup 99/TcO/sub 4//sup -/), a potentially mobile species in leachate from a breached radioactive waste repository, was removed from a brine solution by precipitation with sulfide, iron, and ferrous sulfide at environmental pH's. Maghemite (..gamma..-Fe/sub 2/O/sub 3/) and goethite (..cap alpha..-FeOOH) were the dominant minerals in the precipitate obtained from the TcO/sub 4//sup -/-ferrous iron reaction. The observation of small particle size and poor crystallinity of the minerals formed in the presence of Tc suggested that the Tc was incorporated into the mineral structure after reduction to a lower valence state. Amorphous ferrous sulfide, an initial phase precipitating in the TcO/sub 4//sup -/-ferrous iron-sulfide reaction, was transformed to goethite and hematite (..cap alpha..-Fe/sub 2/O/sub 3/) on aging. The black precipitate obtained from the TcO/sub 4//sup -/-sulfide reaction was poorly crystallized technetium sulfide (Tc/sub 2/S/sub 7/) which was insoluble in both acid and alkaline solution in the absence of strong oxidants. The results suggested that ferrous- and/or sulfide-bearing groundwaters and minerals in host rocks or backfill barriers could reduce the mobility of Tc through the formation of less-soluble Tc-bearing iron and/or sulfide minerals. 12 references, 2 figures, 2 tables.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5876796
- Journal Information:
- Mater. Res. Soc. Symp. Proc.; (United States), Vol. 15
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
GROUND WATER
RADIONUCLIDE MIGRATION
HIGH-LEVEL RADIOACTIVE WASTES
LEACHING
IRON SULFIDES
CHEMICAL REACTIONS
PERTECHNETATES
PRECIPITATION
ANIONS
BRINES
LEACHATES
MINERALS
RADIOACTIVE WASTE DISPOSAL
TECHNETIUM 99
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHALCOGENIDES
CHARGED PARTICLES
DISPERSIONS
DISSOLUTION
ENVIRONMENTAL TRANSPORT
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
IONS
IRON COMPOUNDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MANAGEMENT
MASS TRANSFER
MATERIALS
MIXTURES
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
RADIOISOTOPES
REFRACTORY METAL COMPOUNDS
SEPARATION PROCESSES
SOLUTIONS
SULFIDES
SULFUR COMPOUNDS
TECHNETIUM COMPOUNDS
TECHNETIUM ISOTOPES
TRANSITION ELEMENT COMPOUNDS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
YEARS LIVING RADIOISOTOPES
052002* - Nuclear Fuels- Waste Disposal & Storage
520301 - Environment
Aquatic- Radioactive Materials Monitoring & Transport- Water- (1987)
400702 - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials