Fabrication of zinc oxide nanostructure coated membranes for efficient oil/water separation

A hierarchically structured membrane was fabricated for oil/water separation by effectively depositing ZnO nanoparticles on a glass fiber (GF) membrane. Simple potassium permanganate solution treatment of the GF membranes resulted in the formation of an Mn-(hydroxy)oxide deposit seed layer on the membranes, and then, chemical bath deposition was applied to deposit zinc oxide nanoparticles on the membranes. The scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) showed that ZnO nanostructures were effectively deposited on the membrane surfaces. The ZnO coated membranes were underwater superoleophobic with oil contact angles greater than 150 degrees. An oil-water separation process driven by gravity demonstrated that the membranes could maintain a permeation flux greater than 250 L/m(2)-h with separation efficiencies above 98%. In addition, the ZnO coated membranes exhibited excellent oil/water separation performance in the reusability and durability tests. The results suggest that the ZnO coated membranes possess not only stability but also comprehensive applicability.