COLL 388 |
| Iron (oxyhydr)oxide particles are ubiquitous components of the atmosphere and hydrosphere often encountered in the nanometer size regime. Despite the importance of iron (oxyhydr)oxide surfaces in processes ranging from the biogeochemical cycling of elements to pollutant fate and transport, the influence of particle size on their reactivity in many environmentally relevant systems remains unclear. This is due in part to the wide variety of reactions that can occur on iron (oxyhydr)oxide surfaces (e.g., adsorption, dissolution, and electron transfer), and the possibility that only some of these interfacial processes are a function of particle size. Here, we discuss a series of experiments focusing on the interactions of oxalate with goethite surfaces for particles in the micron- and nanometer-size range (microrods and nanorods, respectively). Specifically, oxalate adsorption, oxalate-promoted (dark) goethite dissolution, and the oxalate-mediated photochemical reduction of goethite were examined in aqueous systems. Complementary to these thermodynamic and kinetic measurements, spectroscopic (ATR-FTIR and XPS) and microscopic (TEM) characterization provided molecular-level insights into the surface properties that could be responsible for reactivity differences observed between nanorods and microrods. Furthermore, light scattering techniques were used to investigate the possible impact of particle aggregation on these interfacial processes. |
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The Physical Chemistry of Environmental Interfaces
2:00 PM-6:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 225, Oral
Division of Colloid & Surface Chemistry |