GEOC 146 |
| Moira K. Ridley, Department of Geosciences, Texas Tech University, P.O. Box 41053, Lubbock, TX 79409-1053, Michael L. Machesky, Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL 61820-7495, Zhan Zhang, Northwestern University, 2225 N. Campus Drive, Evanston, IL 60208, Paul Fenter, Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439, and David J. Wesolowski, Chemical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6110. |
| Macroscopic ion adsorption data for the adsorption of Y(III) to rutile over a range of solid:solution ratios were obtained from potentiometric surface titrations in NaCl media. Two independent sets of sorption data were obtained, the first provided net proton charge isotherms, and the second adsorption “pH-edge” curves. At all conditions, Y(III) sorption decreased the apparent pHznpc, indicating specific ion adsorption involving chemical as well as coulombic interactions. Comparable in situ synchrotron X-ray measurements of Y(III) sorption on rutile (110) single-crystal surfaces have also been performed. The latter measurements indicate Y(III) sorbs as an inner-sphere tetradentate complex at a height of 2.75 ± 0.07 Å above the rutile (110) surface plane. This molecular-scale geometric information was used to uniquely constrain the surface complexation modeling of the bulk titration and adsorption data. This modeling utilized the MUSIC model of surface protonation, coupled with a Stern-based three-layer description of the electric double layer. |
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Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
8:05 AM-11:30 AM, Wednesday, March 31, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |