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This article in SSSAJ

  1. Vol. 18 No. 1, p. 22-25

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Reaction of Phosphate with Kaolinite in Dilute Solution1

  1. Glenn C. Russell and
  2. Philip F. Low2



A typical adsorption curve obeying the Freundlich equation was produced by the adsorption of phosphate on kaolinite. By saturating the exchange complex of the clay with aluminum ions, phosphate adsorption was markedly increased indicating that exchangeable aluminum will react with the added phosphate. Reflectance-wave length curves of aluminon-treated kaolinite revealed the presence of aluminum ions or hydrous aluminum oxide films on the surface of natural kaolinite. This reactive aluminum was reduced by extraction of the clay with aluminum-complexing reagents. The adsorption of phosphate was also reduced by the same treatment. Phosphate adsorption was further reduced by the presence of an aluminum complexing reagent in the phosphate solution reacting with the extracted clay. It was concluded that adsorbed aluminum precipitates the phosphate as an aluminum phosphate on the kaolinite surface.

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