Understanding molecular-scale interactions present at mineral-water interfaces provides insight into numerous environmental processes. MD studies of Na-hectorite interlayer galleries as well as Ca-, Cs-, K-, and Na-hectorite surfaces facilitate a molecular-scale picture of the structure, energetics, and dynamics of the interaction among the mineral substrate, ions, and water molecules during hydration and complement our earlier NMR investigations. Classical MD simulations are undertaken to determine the effects of increasing hydration with focus on the single- and double-layer hydrates during interlayer hydration and on the effects of charge-balancing cations at the surface. Substantial changes occur in the hydration of the charge-balancing cations, the orientations of the water molecules, the hydrogen bond network involving the water molecules and basal O atoms, and the resulting potential energies as the interlayer gallery expands. Macroscopic observables such as the bonding environment of cations and diffusion coefficients are calculated, and computational results from these studies corroborate experiments.

Structure, energetics, and dynamics of smectite clay hydration: Molecular dynamics investigations of hectorite

245th National Meeting (2013)

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