Silicate and Phosphate Adsorption on Gibbsite Studied by X-ray Photoelectron Spectroscopy Angular Distributions1
- Robustiano Alvarez2,
- Charles S. Fadley3 and
- James A. Silva2
A surface-sensitive technique based on the angular distributions of X-ray photoelectron intensities has been used to study the adsorption pattern of Ca, Si and P on gibbsite surfaces. The profile distributions of ions extending from the average Al(OH)3 surface plane appear to be in the order: Ca closer to the surface than Si for CaSiO3 as adsorbate and Ca at nearly the same plane and above Si for CaCl2 + Si(OH)4 as adsorbates irrespective of adsorbate pH. The average positions, relative to the Al(OH)3 atoms are: Si and P appear above the surface level when adsorbed from their respective acid forms, as is the case for more complex adsorbates like Si(OH)4 + H3PO4 + CaCl2, where Ca appears at the surface level. An atomic rearrangement on the gibbsite surface seems to occur in the latter case. These experiments have demonstrated that it is possible to apply the XPS (X-ray photoelectron spectroscopy) angular distribution technique for adsorption studies on powdered soil materials, a subject of relevant interest in earth sciences.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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