GEOC 70 |
| Michael L. Machesky1, James D. Kubicki2, A. V. Bandura3, Milan Predota4, David J. Wesolowski5, Moira K. Ridley6, and Pascale Bénézeth5. (1) Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL 61820-7495, (2) Department of Geosciences, Pennsylvania State University, 308 Deike Bldg, University Park, PA 16802, (3) St. Petersburg State University, St. Petersburg, Russia, (4) Department of Health Physics and Biophysics, University of South Bohemia, Jirovcova 24, Ceske Budejovice, 37004, Czech Republic, (5) Chemical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6110, (6) Department of Geosciences, Texas Tech University, P.O. Box 41053, Lubbock, TX 79409-1053 |
| The molecular-level details of water structure and cation coordination at the rutile (110) surface are being revealed by coordinated ab initio and molecular dynamic calculations. The focus of this presentation will be to illustrate how these calculations are being incorporated into the development of more realistic macroscopic surface complexation models (SCMs). For example, molecular dynamic simulations indicate that the H-bonds formed between surface oxygens and associated water molecules can have different lengths than those in bulk water and this impacts surface protonation constants as estimated with the Revised MUSIC Model. Also, adsorbed Zn2+ heights and bonding geometries as provided by X-ray standing wave measurements are closely matched by ab initio calculations provided that adsorbed Zn2+ is tetrahedral. Moreover, this coordination state change (from octahedral in bulk water) is accompanied by hydrolysis of the adsorbed Zn2+ which in turn can be directly accommodated in SCMs that closely match macroscopic Zn2+ adsorption data. |
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Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
8:00 AM-11:40 AM, Tuesday, March 30, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |