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 geothite (..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 oxidents. 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.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6633547
- Report Number(s):
- CONF-821107-32; ON: DE83003418
- Resource Relation:
- Conference: 6. international symposium on the scientific basis for radioactive waste management, Boston, MA, USA, 1 Nov 1982
- Country of Publication:
- United States
- Language:
- English
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IRON SULFATES
CHEMICAL REACTIONS
PERTECHNETATES
PRECIPITATION
BRINES
HIGH-LEVEL RADIOACTIVE WASTES
IRON
IRON SULFIDES
LEACHATES
LEACHING
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TECHNETIUM 99
ALKALI METAL COMPOUNDS
BETA DECAY RADIOISOTOPES
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CHALCOGENIDES
DISPERSIONS
DISSOLUTION
ELEMENTS
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
IRON COMPOUNDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MATERIALS
METALS
MIXTURES
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
RADIOISOTOPES
SEPARATION PROCESSES
SODIUM COMPOUNDS
SOLUTIONS
SULFATES
SULFIDES
SULFUR COMPOUNDS
TECHNETIUM COMPOUNDS
TECHNETIUM ISOTOPES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
WASTES
YEARS LIVING RADIOISOTOPES
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