The Vanishing water/oil interface in the presence of antagonistic salt

Gudrun Glende; Astrid S de Wijn; Faezeh Pousaneh

doi:10.1063/1.5142811

The Vanishing water/oil interface in the presence of antagonistic salt

J Chem Phys. 2020 Mar 31;152(12):124707. doi: 10.1063/1.5142811.

Authors

Gudrun Glende¹, Astrid S de Wijn¹, Faezeh Pousaneh¹

Affiliation

¹ Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway.

PMID: 32241126
DOI: 10.1063/1.5142811

Abstract

Antagonistic salts are salts that consist of hydrophilic and hydrophobic ions. In a binary mixture of water and an organic solvent, these ions preferentially dissolve into different phases. We investigate the effect of an antagonistic salt, tetraphenylphosphonium chloride PPh₄ ⁺Cl^-, in a mixture of water and 2,6-lutidine by means of Molecular Dynamics (MD) simulations. For increasing concentrations of the salt, the two-phase region is shrunk and the interfacial tension in reduced, in contrast to what happens when a normal salt is added to such a mixture. The MD simulations allow us to investigate in detail the mechanism behind the reduction of the surface tension. We obtain the ion and composition distributions around the interface and determine the hydrogen bonds in the system and conclude that the addition of salt alters the hydrogen bonding.