GEOC 92 |
| Andrew S. Madden and Michael F. Hochella Jr. Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061 |
| The rate of Mn2+(aq) oxidation on hematite surfaces in the presence of oxygenated water has been studied as a function of the hematite particle size, where the particles are in the nanometer size regime. Experimental results from this study suggest that the surface area normalized initial heterogeneous manganese oxidation rate is approximately one to one and a half orders of magnitude greater on hematite particles with average diameter and thickness of 7.3 nm and 1.5 nm than those with average dimensions of 37 nm by 8 nm. The acceleration of electron transfer rate for the reaction promoted by the smallest particles was rationalized in the framework of electron transfer theory, considering the effects of the changing surface geometric and electronic structure on the coupling between solid-Mn-O2, the reduction in reorganization energy for distorted octahedral Mn coordination environments, and the redox potential of the adsorbed Mn. |
|
Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
1:00 PM-5:50 PM, Tuesday, March 30, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |