High flux ethanol dehydration using nanofibrous membranes containing graphene oxide barrier layers

In this study, pristine multilayered graphene oxide (GO) was coated by established methods onto a thin-film nanofibrous composite (TFNC) mat to form a high flux membrane for ethanol dehydration. The thickness of the GO layer was controlled from 90 to 300 nm by taking advantage of the self-assembly behavior of GO sheets. The low transfer barrier of the TFNC mat provides a distinct advantage due to its large bulk porosity (80%) with fully interconnected pore structures. Ethanol dehydration experiments showed that a 93 nm thick GO membrane had a permeate flux of 2.2 (kg m^-2 h^-1) and a separation factor of 308 with a feed solution containing 80 wt% ethanol and 20% water at 70°C, making the GO-TFNC system superior to commercial polymeric membranes. For example, the permeate flux of GO-TFNC is twice as high as that of the polyvinyl alcohol (PVA)-based commercial membrane. The morphology of the GO-TFNC membrane and the mechanism of water transport in the GO layer were also elucidated using SEM, TEM and grazing incidence wide-angle X-ray scattering (GIWAXS) techniques.