The Nature of the Phosphate-Goethite (α-FeOOH) Complex Formed with Ca(H2PO4)2 at Different Surface Coverage1
- R. L. Parfitt2
Basic information on the reaction between Ca(H2PO4)2, NaH2PO4, H3PO4, and the iron oxide goethite (α-FeOOH) has been obtained prior to a study of the desorption of phosphate by plants. Infrared spectra of the wet phosphate-goethite complexes suggested that the binuclear bridging complex was present with all these phosphates over the whole range from low surface coverage to maximum surface coverage. Maximum adsorption was observed when Ca(H2PO4)2 was used with 0.01M CaCl2 as the supporting electrolyte. The adsorption isotherms with phosphate and fluoride (NaF) reached a maximum value which indicated that there were 460 to 480 µmol of reactive A type OH groups on geothite. There was no evidence for phosphate adsorbed in any other form than the surface bridging complex which is formed very rapidly.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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