Biomimetic Multilayer Nanofibrous Membranes with Elaborated Superwettability for Effective Purification of Emulsified Oily Wastewater

Creating a porous membrane to effectively separate the emulsified oil-in-water emulsions with energy saving property is highly desired but remains a challenge. Herein, a multilayer nanofibrous membrane was developed with the inspiration of the natural architectures of earth for gravity-driven water purification. As a result, the obtained biomimetic multilayer nanofibrous membranes exhibited three individual layers with designed functions; they were the inorganic nanofibrous layer to block the serious intrusion of oil to prevent the destructive fouling of the polymeric matrix; the submicron porous layer with designed honeycomb-like cavities to catch the smaller oil droplets and ensures a satisfactory water permeability; and the high porous fibrous substrate with larger pore size provided a template support and allows water to pass through quickly. Consequently, with the cooperation of these three functional layers, the resultant composite membrane possessed superior anti-oil-fouling property and robust oil-in-water emulsion separation performance with good separation efficiency and competitive permeation flux solely under the drive of gravity. The permeation flux of the membrane for the emulsion was up to 5163 L m(-2) h(-1) with a separation efficiency of 99.5%. We anticipate that our strategy could provide a facile route for developing a new generation of specific membranes for oily wastewater remediation.