Anion retention in soil: Possible application to reduce migration of buried technetium and iodine

Technical Report · Tue Oct 01 04:00:00 EDT 1991

DOI:https://doi.org/10.2172/5980032· OSTI ID:5980032

Gu, B; Schulz, R K ^[1]

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1. California Univ., Berkeley, CA (United States). Dept. of Soil Science

This report summarizes a literature review of our present knowledge of the anion exchange properties of a number of soils and minerals, which may potentially be used as anion exchangers to retard migration of such anions as iodide (I{sup {minus}}), iodate (IO{sub 3}{sup {minus}}) and pertechnetate (TcO{sub 4}{sup {minus}}) away from disposal site. The amorphous clays allophane and imogolite, are found to be among the most important soil components capable of developing appreciable amounts of positive charge for anion exchange even at about neutral pH. Decreases in the SiO{sub 2}/Al{sub 2}O{sub 3} ratio and soil pH result in an increase in soil AEC. Allophane and imogolite rich soils have an AEC ranging from 1 to 18 meq/100g at pH about 6. Highly weathered soils dominated by Fe and Al oxides and kaolinite may develop a significant amount of AEC as soil pH falls. The retention of iodine (I) and technetium ({Tc}), by soils is associated with both soil organic matter, and Fe and Al oxides, whereas sorption on layer silicate minerals in negligible. Fe and Al oxides become more important in the retention of anionic I{sup {minus}}, IO{sub 3}{sup {minus}}, and TcO{sub 4}{sup {minus}} as pH falls, since more positive charge is developed on the oxide surfaces. Although few studies, if any, have been conducted on I and {Tc} sorption by soil allophane and imogolite, it is estimated that a surface plough soil (2 million pounds soil per acre) with 5 meq/100g AEC, as is commonly found in andisols, shall retain approximately 5900 kg I and 4500 kg {Tc}. It is conceivable that an anion exchanger such as an andisol could be used to modify the near field environment of a radioactive waste disposal facility. This whole disposal system would then offer similar migration resistance to anions as is normally afforded to cations by usual and normal soils. 93 refs., 10 figs., 7 tabs.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Regulatory Applications; California Univ., Berkeley, CA (United States). Dept. of Soil Science
• Sponsoring Organization: NRC; Nuclear Regulatory Commission, Washington, DC (United States)
• OSTI ID: 5980032
• Report Number(s): NUREG/CR-5464; ON: TI92002690
• Country of Publication: United States
• Language: English

Related Subjects

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Terrestrial-- Radioactive Materials Monitoring & Transport-- (1990-)
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
CLAYS
CRYSTAL STRUCTURE
ELECTROLYTES
ELEMENTS
ENVIRONMENTAL TRANSPORT
GROUND WATER
HALOGENS
HYDROGEN COMPOUNDS
IODINE
ION EXCHANGE
IRON COMPOUNDS
IRON OXIDES
KINETICS
LOW-LEVEL RADIOACTIVE WASTES
MANAGEMENT
MASS TRANSFER
MATERIALS
METALS
MICROSTRUCTURE
MITIGATION
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
RADIONUCLIDE MIGRATION
REACTION KINETICS
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SOILS
SORPTIVE PROPERTIES
SUBSURFACE ENVIRONMENTS
SURFACE PROPERTIES
TECHNETIUM
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
UNDERGROUND DISPOSAL
VALENCE
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
WEATHERING