Premium
Phosphate Sorption by Soils: I. A Model for Phosphate Reaction with Metal‐Oxides in Soil
Author(s) -
Riemsdijk W. H.,
Boumans L. J. M.,
Haan F. A. M.
Publication year - 1984
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/sssaj1984.03615995004800030013x
Subject(s) - sorption , gibbsite , phosphate , diffusion , soil water , chemistry , oxide , metal , inorganic chemistry , adsorption , materials science , mineralogy , thermodynamics , geology , organic chemistry , soil science , kaolinite , physics
A model for P sorption is described which is based on previous studies concerning the interaction of phosphate with gibbsite and with a sandy soil. Formation of coatings of metal phosphate on metal oxide particles constitutes the presumed mechanism of the sorption process. Diffusion of phosphate ions through the surface coating is taken as the rate‐limiting step. The relating diffusion equation is first solved with the condition of constant concentration for reactive particles of well defined geometry. Then it is shown that for any assembly of reactive particles the sorption as a function of the concentration‐time product should yield one curve, irrespective of the reaction pathway. The form of this curve can only be predicted for very specific cases. The above curve, however, can be determined experimentally, allowing the calculation of the phosphate sorption rate for any combination of concentration and sorption values. This is very useful in modeling the transport of P through soil systems. Experimental evidence is given which supports the model theory.