Molecular dynamics study of pervaporation of water–methanol mixtures through graphene nanotubes

Abstract

By means of extensive molecular dynamics simulations, we explore the concentration enhancement of alcohol from water/methanol solutions induced by the preferential flow of alcohols through single-layer carbon nanotubes of various widths. These nanotubes connect a reservoir containing an aqueous methanol solution with an empty reservoir. Simulations are performed at room temperature and at 398 K. The non-equilibrium stages of these simulations can represent a rough model of the pervaporation process through a hydrophobic membrane channel. Once equilibrium is reached in the receiving reservoir, we observe a substantial increase in alcohol concentration with respect to the value that would correspond to the gas phase in an unconfined vapor–liquid equilibrium at the same temperature. Alcohol yields are particularly high when starting from dilute alcohol solutions and for nanotubes 2–3 times wider than the average adsorbate molecular size.