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Direct calculation of the planar NaCl-aqueous solution interfacial free energy at the solubility limit

Accepted version
Peer-reviewed

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Authors

Rene Espinosa, Jorge  ORCID logo  https://orcid.org/0000-0001-9530-2658
Sanchez-Burgos, Ignacio 

Abstract

Salty water is the most abundant electrolyte aqueous mixture on Earth, however, very little is known about the NaCl-saturated solution interfacial free energy (γs). Here, we provide the first direct estimation of γs for several NaCl crystallographic planes by means of the Mold Integration technique, a highly efficient computational method to evaluate interfacial free energies with anisotropic crystal resolution. Making use of the JC-SPC/E model, one of the most benchmarked force fields for NaCl/water solutions, we measure γs of four different crystal planes, (100), (110), (111), and (112) with the saturated solution at normal conditions. We find high anisotropy between the different crystal orientations with values ranging from 100 to 150 mJ m−2, and the average value of the distinct planes being γs = 137(20) mJ m−2. This value for the coexistence interfacial free energy is in reasonable agreement with previous extrapolations from nucleation studies. Our work represents a milestone in the computational calculation of interfacial free energies between ionic crystals and aqueous solutions.

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Journal Title

Physical Review Letters

Conference Name

Journal ISSN

0031-9007

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Publisher

American Physical Society

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Sponsorship
EPSRC.