Surface acidity plays a central role in the chemical processes occurring at the solid/liquid interface. Because of the inherent difficulty for titration measurements to distinguish between the contributions of various functional groups, modeling of surface acidity has always played an important role in the understanding of relevant quantities, such as the pH at the point of zero charge. The currently most used and successful models for surface acidity are parametrized empirical models, where starting from solution monomer acidity further structural information is incorporated and translated in prediction of chemical behavior. However differentiating between specific surface site geometries as well as accounting for the local solvation structure can be difficult for empirical models.In this contribution we present our recently developed method to calculate surface acidity based on first principles molecular dynamics simulations, a parameter-free approach which is particularly suitable to describe the heterogeneous environment of solid/liquid interfaces naturally including the specific hydrogen bonds to water and polarization effects.We will discuss some applications to interfaces of interest to the geochemistry community. In particular in the case of silica, the most abundant solid compound in the earth crust, we provides a microscopic understanding of the bi-modal behavior observed in titration experiments[1]. We also describe the surface acidity of different naturally occurring oxides, such as aluminum oxide[2] and hydroxide[3], clays[4], titania[5] and man-made materials, such as hydrated cement[7]. [1]M.Sulpizi, M.-P.Gaigeot, M.Sprik J.Chem.TheoryComput., 8(3), 1037 (2012)[2]M.-P. Gaigeot, M. Sprik, M. Sulpizi J.Phys.Cond.Matt. 24(12), 124106 (2012)[3]X.D. Liu, J Cheng,M. Sprik, X.C. Lu, R.C. Wang, Geochimica et Cosmochimica Acta, 120, 487 (2013)[4]S. Tazi, B. Rotenberg, M. Salanne, M. Sprik, M. Sulpizi Geochimica et Cosmochimica Acta, 94, 1 (2012)[5]J. Cheng, M. Sulpizi, J. VandeVondele, M. Sprik ChemCatChem 4(5) 636 (2012)[6]S.V. Churakov, C. Labbez, L. Pegado, M. Sulpizi under review in J.Phys.Chem.

Surface acidity from first principle simulations

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.