ENVR 31 |
| James D. Kubicki and Heath D. Watts. |
| Hybrid molecular orbital/density functional theory (MO/DFT) calculations were performed using Gaussian 03 on model aqueous and surface arsenic species. As(III) and As(V) were modeled in both monodentate and bidentate bridging configurations in various states of protonation and hydration with Al- and Fe-hydroxide dimer clusters. Estimates of the relative Gibbs free energy changes of adsorption were consistent with the observed preference of As(III) for hydrous ferric oxide (HFO) over Al-based phases. Calculated results were compared to interatomic distances derived from EXAFS spectra and vibrational frequencies from IR and Raman spectra. The bidentate bridging configuration is most consistent with spectroscopic data, but the model Gibbs free energies of adsorption suggest that the monodentate configuration may also be stable depending upon conditions. |
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Occurrence, Chemistry, Toxicity and Remediation of Arsenic
1:30 PM-4:50 PM, Sunday, 26 March 2006 Georgia World Congress Center -- B218, Oral
Division of Environmental Chemistry |