J. Phys. IV France 7 (1997) C2-823-C2-824
EXAFS Study of Zn and ZnEDTA Sorption at the Goethite (α-FeOOH)/Water InterfaceM.L. Schlegel, A. Manceau and L. Charlet
Environmental Geochemistry Group, LGIT-IRIGM, UJF, BP. 53, 38041 Grenoble cedex 9, France
EXAFS spectroscopy has been used to compare the sorption mechanism of Zn and ZnEDTA on goethite (α-FeOOH). In the absence of EDTA, Zn is found to form an inner-sphere surface complex. Based on Zn-O and Zn-Fe distances, Zn is inferred to be located in a distorted oxygen octahedron which shares edges and/or corners with surface Fe octahedra. EXAFS spectra of ZnEDTA in solution and sorbed on goethite are similar, indicating that the ZnEDTA complex does not dissociate following its sorption. The absence of an Fe shell within the first 4 Å precludes the existence of Zn-O-Fe bonds and allows us to reject a ligand exchange sorption rnechanism involving the formation of Zn-O-Fe linkages.
© EDP Sciences 1997