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Interaction of Ethanol and Water with the {101̅4} Surface of Calcite

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journal contribution
posted on 21.09.2010, 00:00 authored by D. J. Cooke, R. J. Gray, K. K. Sand, S. L. S. Stipp, J. A. Elliott
Molecular dynamics simulations have been used to model the interaction between ethanol, water, and the {101̅4} surface of calcite. Our results demonstrate that a single ethanol molecule is able to form two interactions with the mineral surface (both Ca−O and O−H), resulting in a highly ordered, stable adsorption layer. In contrast, a single water molecule can only form one or other of these interactions and is thus less well bound, resulting in a more unstable adsorption layer. Consequently, when competitive adsorption is considered, ethanol dominates the adsorption layer that forms even when the starting configuration consists of a complete monolayer of water at the surface. The computational results are in good agreement with the results from atomic force microscopy experiments where it is observed that a layer of ethanol remains attached to the calcite surface, decreasing its ability to interact with water and for growth at the {101̅4} surface to occur. This observation, and its corresponding molecular explanation, may give some insight into the ability to control crystal form using mixtures of different organic solvents.

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