Premium
Phosphorus Adsorption by Kaolinite and Montmorillonite: I. Effect of Time, Ionic Strength, and pH
Author(s) -
BarYosef B.,
Rosenberg Rivka,
Kafkafi U.,
Sposito G.
Publication year - 1988
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1988.03615995005200060011x
Subject(s) - adsorption , kaolinite , ionic strength , chemistry , montmorillonite , phosphate , phosphorus , electrolyte , inorganic chemistry , soil water , langmuir adsorption model , mineralogy , aqueous solution , geology , organic chemistry , soil science , electrode
Phosphate reactions in soils are affected by various factors operating simultaneously. The objective of this work was to study specific effects of total P concentration, pH, ionic strength, and equilibration time on P partitioning between solid and solution phases of Ca‐ and K‐kaolinite and ‐montmorillonite suspensions as model systems of soils containing these minerals. Phosphorus concentration in the solution phase ( C p ) stabilized within 24 to 48 h after introducing P into the system. Increased electrolyte concentration, which elevated the electrical conductivity (EC) from 0.2 to 5.0 dS/m, decreased C p in both clay systems. Further increase to about 40 dS/m had a negligible effect on C p . Phosphorus adsorption by Ca‐clay exceeded that by K‐clay. This, and the effect of EC on C p are suggested to operate via their effect on the extent of the diffuse double layer, which determine the accessibility of P to adsorption sites on clays' edges. Phosphorus solution concentration as a function of pH was minimal in the studied clays around pH 6. In the investigated pH range (5–9), P partitioning was controlled by adsorption, which could be described by a modified Langmuir model. The model accounts for effects of C p and pH on adsorption and considers retention of individual P species by the adsorbent.