Phosphate Adsorption on an Oxisol1
- R. L. Parfitt2
Adsorption isotherms for phosphate on the A and B horizon of an oxisol from Papua New Guinea showed high affinity adsorption at low solution concentrations and a linear increase in adsorption at higher solution concentrations. Adsorption increased with decrease in pH in the range 3 to 8. Comparison with data obtained under similar conditions with synthetic goethite (α-FeOOH) and gibbsite [Al(OH)3] suggested that phosphate reacted with FeOH and FeOH2+ groups on soil iron oxide surfaces to form a binuclear bridging FeOP(O2)OFe complex and with exposed Al(OH)H2O on kaolinite edges and on hydroxy-aluminum species to form a binuclear or bidentate phosphate complex. At higher phosphate concentrations isotherms showed continued adsorption which may be due to a further reaction involving hydroxy-aluminum groups.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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