Boron adsorption and silicon release by the clay minerals kaolinite, montmorillonite, and illite
Boron adsorption behavior on the clay minerals kaolinite, montmorillonite, and illite was investigated. Adsorption increased at low pH, exhibited a peak in the pH range 8 to 10, and decreased at high pH. It was assumed that B adsorbs by means of a ligand exchange mechanism with aluminol groups at the edges of the clay particles. The constant capacitance model was able to describe B adsorption on kaolinites over the entire pH range studied (3-12), using only one adjustable parameter: the boron surface complexation constant. The model was able to fit B adsorption on montmorillonites and illites using three adjustable parameters; however, the chemical significance of some of the surface complexation constants in uncertain. Silicon release to solution increased in the order: kaolinite << illite < montmorillonite and exhibited a minimum in the pH range 8 to 9. Boron adsorption on kaolinites was reduced only slightly in the presence of added silicate despite considerable silicate adsorption. Boron adsorption on montmorillonites was unaffected by the presence of added silicate. It is suggested that B and silicate adsorb on specific sites and that little anion competition occurs.
- Research Organization:
- Dept. of Agriculture, Riverside, CA
- OSTI ID:
- 6622239
- Report Number(s):
- CONF-8611156-
- Journal Information:
- Soil Sci. Soc. Am. J.; (United States), Vol. 50:6; Conference: 50. annual meeting of the Soil Science Society of America, New Orleans, LA, USA, 30 Nov 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BORON
ADSORPTION
SOIL CHEMISTRY
SILICON
ANIONS
CLAYS
ILLITE
KAOLINITE
MATHEMATICAL MODELS
MONTMORILLONITE
PH VALUE
SOILS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CHARGED PARTICLES
CHEMISTRY
ELEMENTS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IONS
MATERIALS
MINERALS
OXYGEN COMPOUNDS
SEMIMETALS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SORPTION
510200* - Environment
Terrestrial- Chemicals Monitoring & Transport- (-1989)