Phase separation of liquid mixtures inside carbon nanotubes*

Ethanol and water are permeable through carbon nanotubes (CNTs). However, in the case of water-ethanol mixtures, distinct layers (or domains) of water and ethanol form inside these nanotubes due to the higher affinity of the ethyl group of ethanol towards carbon [1] and the hydrophobicity of CNTs. Additionally, due to confinement effects on water [2] and ethanol, phase separation may occur depending on the pressure, temperature, and mixing entropy of liquids. In this study, we will analyze the phase separation and formation of domains in liquid mixtures, primarily of ethanol and water, occurring inside CNTs, using ab-initio molecular dynamics (AIMD) to capture both the quantum mechanical effects due to confinement of liquids and the dynamical evolution of these systems. Studying the phase separation of liquid mixtures under confinement may help develop membrane technology for efficient separation of miscible polar liquids and water.
[1] J. Chem. Phys. 145, 124708 (2016)
[2] J. Phys. Chem. C 2016, 120, 26, 14209–14215