J. Phys. IV France 7 (1997) C2-825-C2-826
XAFS Studies of Pb(II)-Chloro and Hg(II)-Chloro Ternary Complexes on GoethiteJ.R. Bargar1, 2, P. Persson3 and G.E. Brown Jr.1
1 Department of Geological and Environmental Sciences, Stanford University Stanford CA 94305-2115, U.S.A.
2 US Geological Survey, 345 Middlefield Road, MS 465, Menlo Park CA 94025, U.S.A.
3 Department of Inorganic Chemistry, Umeå University, 90187 Umeå, Sweden
EXAFS spectroscopy was used to study Pb(II) and Hg(II) adsorption complexes on goethite (α-FeOOH) in the presence of Cl-. At pH 7, the dominant Pb(II) species are bonded to edges of FeO6 octahedra and are similar to complexes that occur in the absence of Cl-. At pH≤6, Pb(II)-chloro ternary complexes pedominate and are bonded to corners of FeO6 octahedra. At pH 6.5, linear Hg(OH)Cl ternary complexes predominate that are bonded to goethite through surface oxygens in a bent Hg-O-Fe geometry. In the absence of Cl-, the Hg(II) surface complexes retain this basic geometry, but an OH group replaces the chloride ion in the first coordination shell.
© EDP Sciences 1997