High-Flux Graphene Oxide Membranes Intercalated by Metal-Organic Framework with Highly Selective Separation of Aqueous Organic Solution.

Graphene oxide (GO) membranes assembled by single-atom thick GO nanosheets have displayed huge potential application both in gas and liquid separation processes due to its facile and large-scale preparation resulting from various functional groups, such as hydroxyl, carboxyl, and epoxide groups. Taking advantage of these characters, GO membranes intercalated by superhydrophilic metal-organic frameworks (MOFs) as strengthening separation fillers were prepared on modified polyacrylonitrile (PAN) support by a novel pressure-assisted self-assembly (PASA) filtration technique instead of traditional vacuum filtration method for the first time. The synthesized MOF@GO membranes were characterized with several spectroscopic techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), as well as scanning electron microscopy (SEM). Compared with GO membrane, these MOF@GO membranes combine the unique properties of MOF and GO and thus have significant enhancements of pervaporation (PV) permeation flux and separation factor simultaneously for ethyl acetate/water mixtures (98/2, w/w) through the PV process, which are also superior to the reported other kinds of membranes. Especially, for MOF@GO-0.3 membrane (corresponding MOF loading: 23.08 wt %), the increments are 159% and 244%, respectively, at 303 K, and the permeate water content can reach as high as 99.5 wt % (corresponding separation factor, 9751) with a high permeation flux of 2423 g m-2 h-1. Moreover, the procedures of both the synthesis of MOF and membranes preparation are environmentally friendly that only water was used as solvent. Such a nanosized MOF-intercalating approach may be also extended to other laminated membranes, providing valuable insights in designing and developing of advanced membranes for effective separation of aqueous organic solution through nanostructure manipulation of the nanomaterials.