Effect of inorganic and organic ligands on the mechanism of cadmium sorption to goethite
Extended X-ray Absorption Fine Structure (EXAFS) spectroscopic data for Cd{sup 2+} sorbed on goethite in the presence of phosphate, sulfate and humate indicate that cadmium is surrounded by a first shell of {approximately}6 {+-} 1 O atoms at 2.3 {+-} 0.1 {angstrom}. A second shell is approximately 2 Fe atoms at 3.8 {+-} 0.1 {angstrom} is also observed. These interatomic distances suggest that Cd{sup 2+} is inner-spherically bound by bidentate double-corner-sharing adsorption on the (110) surface of goethite. In contrast, Cd{sup 2+} appears to form a precipitate in the presence of citrate and oxalate. The enhancement of Cd{sup 2+} adsorption in the presence of sulfate and phosphate is solely by electrostatic interaction, implying that the ligands sorb to sites other than those occupied by Cd{sup 2+}. No ternary complexes are observed in the presence of these 2 inorganic ligands.
- Research Organization:
- Univ. of Bristol (GB)
- OSTI ID:
- 20003960
- Journal Information:
- Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: 19-20 Vol. 63; ISSN GCACAK; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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