COLL 110 |
| Rhodochrosite (MnCO3) is an important component of anoxic soils and sediments. At the oxic/anoxic interface, rhodochrosite surface can be oxidized by dissolved oxygen and form oxide structures (MnOx) of a few nanometers high. Our previous research found that these nanostructures had surface potentials several hundred millivolts higher than the rhodochrosite substrate in humid air. Using in-situ force-volume atomic force microscopy (AFM), we now show that the nanostructures exhibit different interfacial forces in aqueous solution, compared to the rhodochrosite substrate. The interfacial forces that we have characterized include hydration force, van de Waals attraction, and electrostatic repulsion. Ionic strength and solution pH are varied in the experiments to explore the effects of these important environmental regulators. Our results reveal that reaction with dissolved oxygen induces changes of surface chemistry on rhodochrosite, which, in turn, are expected to influence contaminant adsorption and bacterial attachment.
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The Physical Chemistry of Environmental Interfaces
2:00 PM-5:20 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. 225, Oral
Division of Colloid & Surface Chemistry |
