GEOC 56 |
| Goethite is among the most significant iron oxyhydroxide minerals on the surface of the earth. It is one of the major reactive mineral phases in lakes and marine sediments, and has long been known as a major reactive phase in soils. Accordingly goethite(alpha-FeOOH) has been studied intensely as a substrate for metal and anion sorption, organic molecule sorption, and reactions with soil bacteria. Additionally, goethite is one of the principal phases used to develop models for sorption reactions, which rely on the assumption that the surface structure of goethite is perfectly described by the bulk structure termination. Despite its importance, the surface structure of goethite prior to this work was unknown. Surface structure methods such as Crystal Truncation Rod (CTR) scattering capable of exploring the liquid solid interface where hindered due to the lack of large low roughness single crystal surfaces. However, recently we were able to cleave from a large goethite specimen a small (1 x 1 mm2) “chip” with a good (100) surface and for the first time measured a high quality CTR data set. Such CTR scattering data provide a valuable view of both the surface substrate relaxations and location of absorbed surface complexes. We will discuss our surface structure determination of goethite(100) and the continuing work on the hydrated (100) surface, examining the response to varied pH, and the sorption of arsenate. |
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Frontiers in Geochemistry: Commemorating the 25th Anniversary of the ACS-Geochemistry Division
9:00 AM-12:00 PM, Monday, 11 September 2006 Moscone Center -- Room 262, Oral
Sci-Mix
Division of Geochemistry |