Extension of PC-SAFT equation of state to include mineral surface effect in fluid properties using molecular dynamic simulation
SA Goltapeh and S Abdolahi and R Miri and H Hellevang, SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS, 48, 101624 (2021).
In the vicinity of fluid-mineral interfaces a transition zone exist in which the order and packing of the molecules differ from that of the bulk phase where the distribution of intermolecular forces exhibit a more homogenous form. To develop an understanding of the thermodynamic properties in the fluid-mineral interface molecular dynamic (MD) simulation was conducted for the water-calcite system. To predict the water properties near the calcite wall, we have defined a contribution for Helmholtz energy extended from PC-SAFT equation of state (EOS). The new energy contribution depends on the confinement parameters i.e. potential of fluid-wall interaction, confinement degree, bulk density, and fraction of confined molecules estimated by MD simulation. The outcomes of MD simulation exhibit the layering transition of water on the water-calcite interface. In addition, MD simulation confirm the energy deviation within the layering transition zone, where the calcite adsorbs the water molecules. In this approach, the modified PC-SAFT showed a good agreement with MD observations. The results of this study can contribute to a better understanding of fluid behavior at the fluid- mineral interface. In addition, this technique is a valuable tool that can be used to estimate solubility limits in multicomponent fluid processing and pipeline transport.
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