Fabrication of Gelatin/Graphene Oxide Ultrathin Hybrid Membrane Via Layer-By-Layer Self-Assembly for Pervaporation Dehydration Process

Fabricating composite membrane with ultrathin, defect-free and stable active layer is an effective method to achieve separation membrane with high permeability, selectivity and stability simultaneously. Layer-by-layer (LBL) self-assembly method provides an attractive option for the fabrication of ultrathin, defect-free membranes with tailored composition and tunable properties. Inspired by the distinctive mechanical properties of nacre from the ordered brick-and-mortar arrangement of organic and inorganic layers, ultrathin hybrid membranes were fabricated via LBL self-assembly of graphene oxide and gelatin for pervaporation dehydration process. Graphene oxide possesses amphiphilic structure with oxygenated polar groups on the basal plane and edge, and the hydrophobic sp² hybridized carbon atoms on backbone. Gelatin is a natural protein composed of various hydrophobic and hydrophilic amino acids. The matching chemical structures of graphene oxide and gelatin endows the formation of multiple interactions between them (including electrostatic attraction, hydrogen bond, and hydrophobic interaction), which differs from the existing researches. The dense interface regions between graphene oxide and gelatin achieved efficient separation of water from ethanol solutions. Moreover, the micrometer-scale size of graphene oxide in horizontal direction favored the coverage of nanopores on substrate, which greatly reduced the required deposition cycles, and thus simplified the membrane-fabrication procedure.