It is crucial to understand mineral-water interface reactivity as it relates to geochemical sorption processes that influence the cycling, bioavailability, and fate of nutrients and contaminants. In this study, the surface energetics of several terminations of (001) and (110) planes of corundum-Al2O3 have been modelled through density functional theory (DFT) method. We have also investigated the inner-sphere adsorption of a number of oxyanions on the (001) and (110) surfaces of corundum-Al2O3 using a DFT-based thermodynamics model. Periodic boundary conditions were applied to mimic the extended crystalline characteristics of the substrate. GBRV pseudopotentials were employed as the basis functions for the periodic GGA-PBE calculations. Specifically, phase diagram, surface energy temperature dependence, and electronic structure properties of these surfaces were examined in the presence and absence of hydration effects for the (001) and (110) surfaces. A systematic inspection of various adsorption modes of oxyanions on the (001) and (110) surface of this mineral was also performed. Optimized geometries, electronic structure, phonons, and energetics were utilized to interpret and complement the experimental X-ray scattering measurements. We use the varying surface terminations of (110) plane to analyze the role of surface functional groups and charging on its energetics and relative stability. Different inner-sphere adsorption cases on the (001) surface were modelled to examine the competitive effect of various species present in the natural aqueous environment. These variables were studied by coupling the DFT results with thermodynamics modelling that includes terms for varying pH and ionic strength.

Using DFT, molecular dynamics, and thermodynamics modelling, to connet with experimental information about Al2O3-water interface structure and reactivity

2019 Spring National Meeting

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