Role of iron oxides in the phosphate adsorption properties of kaolinites from the Ivory Coast
The phosphate adsorption properties of three clay samples, with kaolinite as the dominant mineral, from different deposits in the Ivory Coast have been investigated. The clays contain varying amounts of crystalline Fe oxides and kaolinite with structural Fe. All measurements were made in dilute suspension under controlled conditions of temperature, pH, ionic strength and saturating cation. Data have been fitted to Langmuir adsorption isotherms. Both P adsorption and surface area measurements have been made on samples before and after chemical removal of Fe oxides. The samples have large P adsorption capacities, which are not entirely explained by their large specific surface areas. The presence of Fe oxides makes a strong contribution to the surface area and enhances the adsorption capacities. There is little evidence that structural Fe makes a strong contribution to the enhanced P adsorption capacity.
Key WordsAdsorption Fe Oxide Goethite Hematite Kaolinite Langmuir Phosphate
Unable to display preview. Download preview PDF.
- Cornell, R.M. and Schwertmann, U. (1996) The Iron Oxides: Structure, Properties, Reactions, Occurrence and Uses. VCH Weinheim, New York, 573 pp.Google Scholar
- Parfitt, L.R. (1978) Anion adsorption by soils and soil materials. Advanced Agronomy, 30, 1–50.Google Scholar
- Sei, J. (1998) Etude de matériaux de dimensionalité réduite: Relation structure-propriétés dans des kaolinites naturelle de Cote d’Ivoire. PhD thesis, Univ. Montpellier, France.Google Scholar
- Singh, B. and Gilkes, R.J. (1992) Properties of soil kaolinites from south-western Australia. Journal of Soil Science, 43, 654–667.Google Scholar
- Torrent, J. (1997) Interactions between phosphate and iron oxide. Advances in Geoecology, 30, 321–344.Google Scholar
- White, R.E. (1980) Retention and release of phosphate by soils and soil constituents. In: Soils and Agriculture, Critical Reports on Applied Chemistry, Volume 2. Blackwell Scientific Publications, Oxford, UK.Google Scholar