Fundamental insights about environmental interface reactivity from DFT calculations of geochemical model systems

The fact that essential chemical information about environmental interfaces is becoming accessible through density functional theory (DFT) studies provides researchers with a means to interpret experimental information, to predict properties that cannot be measured, and to develop conceptual, molecular-level understanding of structure-property relationships of these systems. Molecular studies of environmental interfaces require the use of structurally well-defined geochemical models, and in here we discuss the reactivity of mineral-water interfaces and aqueous aluminum hydroxide nanoparticles with ionic species. These adsorption processes are a major factor controlling pollutant transport and transformation. In the examples we highlight, DFT studies are used to extract new conceptual understanding of the underlying physical factors of the substrates that dictate reactivity. In particular, we review DFT studies used to rationalize an empirically determined reactivity trend of hydrated alumina and hematite towards Pb(II), and later review how DFT calculations of aqueous aluminum hydroxide nanoparticles along with experimental structural information helped to identify the electrostatic potential as a key factor in understanding particle reactivity towards cationic and anionic species.