Adsorption of Organic Molecules on Kaolinite from the Exchange-Hole Dipole Moment Dispersion Model

Intermolecular interactions between organic molecules and clay minerals are important in a wide range of chemical applications, ranging from oil-sands petroleum extraction to environmental chemistry and catalysis. The binding energies between each of benzene, n-hexane, pyridine, 2-propanol, and water and the kaolinite surface are calculated using density functional theory with the exchange-hole dipole moment dispersion model. The dominant noncovalent interactions are found to be hydrogen bonding for pyridine, 2-propanol, and water, OH-π interactions for benzene, and CH-O interactions for n-hexane. All molecules considered are more strongly bound to the hydrophilic alumina face, rather than the hydrophobic siloxane face, of kaolinte.