Adsorption of fluoride by soils and minerals
The adsorption of F by soils and common hydroxyl-containing minerals found in soils was studied over a solution concentration range of 2 to 16 mg./l. It was found that gibbsite, kaolinite, halloysite, precipitated Al(OH)/sub 3/, that all soils studied adsorb significant amounts of F with release of OH/sup -/, and that the adsorption is concentration-dependent and described by the Langmuir adsorption equation. At an equilibrium F concentration of 16 mg./l. the adsorption in mg./kg. was as follows: alkaline soils, 59 to 120; acid Aiken soil, 1060; gibbsite and kaolinites, 190 to 295, dehydrated halloysite, 1400; hydrated (expanded) halloysite, 1777; and precipitated Al(OH)/sub 3/, 32,600. Goethite, benonite (montmorillonite) and vermiculite adsorbed only traces of F. The similar adsorption by dehydrated and expanded halloysite, together with the very high F adsorption capacity of precipitated Al(OH)/sub 3/, suggest that F adsorption at low concentrations occurs primarily by exchange with OH of Al(OH)/sub 3/ rather than with the crystal lattice OH of clay minerals. If a soil having high permeability and high F adsorption capacity were available, it might be practical to remove excess F from water for municipal use by adsorption on soil in a system such as that used for ground-water recharge. 10 references, 1 table.
- Research Organization:
- Dept. of Agriculture, Riverside, CA
- OSTI ID:
- 6554215
- Journal Information:
- Soil Sci.; (United States), Journal Name: Soil Sci.; (United States) Vol. 103:3; ISSN SOSCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ADSORPTION
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM HYDROXIDES
ALUMINIUM SILICATES
BENTONITE
CLAYS
DATA
ECOLOGICAL CONCENTRATION
ELEMENTS
EXPERIMENTAL DATA
FLUORINE
GIBBSITE
HALOGENS
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IRON COMPOUNDS
IRON SILICATES
KAOLINITE
LAND POLLUTION
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
MATERIALS
MICA
MINERALS
NONMETALS
NUMERICAL DATA
OXIDE MINERALS
OXYGEN COMPOUNDS
POLLUTION
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SOILS
SORPTION
TRANSITION ELEMENT COMPOUNDS
VERMICULITE