COLL 124 |
| Kathryn L. Nagy1, Michel L. Schlegel2, Paul Fenter3, and Neil C. Sturchio1. (1) Department of Earth and Environmental Sciences, University of Illinois at Chicago, 845 West Taylor St, Chicago, IL 60607-7059, (2) Commissariat a l'Energie Atomique de Saclay, Gif-sur-Yvette, F-91191, France, (3) Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439 |
| The behavior of sorbates and water at silicate mineral surfaces controls many processes in environmental and materials science. We investigated the quartz-water and muscovite-salt solution interfaces using synchrotron-based X-ray reflectivity, which has the unique ability to characterize water structure and consequently the inner-sphere or outer-sphere nature of sorbates. Data were collected at BESSRC-CAT, Advanced Photon Source and converted to electron density profiles perpendicular to the interface. Modeled profiles show that monovalent and divalent cations attach to the muscovite basal surface in the first adsorbed layer with no intervening water. Water layering occurs above the adsorbed layer. On quartz, surface silica groups have only one free Si-O bond each, and there is a single layer of adsorbed water, with no additional layering. Relaxation of atomic positions in both minerals is minimal. The type and amount of charge on the mineral surfaces influence both water and sorbate structure. |
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The Science and Engineering of Catalyst Preparation
8:30 AM-11:55 AM, Monday, March 29, 2004 Marriott -- Orange County 3, Oral
Division of Colloid and Surface Chemistry |