Fabrication of ZnO/PDA/GO composite membrane for high efficiency oil-water separation

Zinc oxide/polydopamine nanoparticles/graphene oxide (ZnO/PDA/GO) membranes are fabricated combining chemical and physical methods. In this process, magnetron sputtering is used to deposit ZnO seed layers for further growing uniform and dense ZnO nanorod arrays by hydrothermal method, and then ZnO nanorod arrays is decorated using PDA and GO. The surface morphologies and microstructure characterization indicate that ZnO/PDA/GO membrane with the layered stacked structures is successfully fabricated. Interestingly, ZnO/PDA/GO membrane not only reduced the pore size compared with the original Cu mesh, but also has hydrophilic/underwater superoleophobicity with an underwater oil contact angle higher than 150 degrees. The oil-water separation process driven by gravity shows that the separation efficiency of the membrane for various oil-water mixtures is more than 99%, and it has excellent corrosion resistance and cycle stability. In addition, based on density functional theory (DFT), the double-sided saturated adsorption of water molecules on the model is constructed. The simulation results confirm theoretically that the oil-water separation of underwater superhydrophobic membrane is indeed due to the formation of hydration layer on the membrane surface. These results provides a new idea for the design and development of functional membranes for oil-water separation.