GEOC 167 |
| Y. Thomas He, Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061 and P. Dove, Department of Geological Sciences, Virginia Polytechnic Institute, Blacksburg, VA 24061. |
| Reliable kinetic models that predict long-term waste glass performance require accurate baseline knowledge of how major solutes and metals affect silica reactivity. The effects of 2+ cations as alkaline earth (Mg, Ca, Sr, Ba) and transition metal (Mn, Co, Cu, Ni, Zn, Cd) elements on the dissolution of amorphous silica, SiO2(am), were determined at 60°ãC in semi-batch reactors at near-neutral pH (pH 5.7). Experimental measurements show that all cations increase SiO2(am) dissolution rates by 10-50 times compared to measurements in DI H2O. The maximum degree of rate enhancement does not correlate with d electron configuration of the metals, but does follow a simple trend that correlates with Z2/r (where r=hydrated radius) and the free energy of hydration of corresponding cations. All cations except nickel follow this relation. Our findings reiterate the possible role of cation solvation properties in mediating the kinetics of Si-O bond hydrolysis. |
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Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
1:20 PM-5:40 PM, Wednesday, March 31, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |