Solvent diffusivity and viscosity in graphene oxide membrane for water-ethanol separation.

Graphene oxide (GO) membranes were recently suggested for applications in separation of ethanol from water using a vapor permeation method. Understanding microscopic diffusivity of water and ethanol in graphene oxide membranes is important for separations applications. It is also important to study the anisotropy of water and ethanol diffusivity between the direction perpendicular to the plane and in-plane direction. We used quasielastic neutron scattering(QENS) to measure the temperature dependence of the diffusivity of water and ethanol, and its anisotropy by the utilization of Q-dependence of QENS signals obtained from BASIS at Oak Ridge National Lab. We will also discuss how dynamic measurements from QENS can be correlated with atomic force microscopy measurements of the temperature dependence of viscosity in water/ethanol confined in GO.