An adaptive and fast emulsion separation Janus membrane

Abstract

Inspired by the capillary effect in nature (such as water transport in soils) and droplet-drive performance of Nepenthes, a new driving strategy for emulsion separation membrane based on the synergistic effect of capillary force and progressive wettability-induction force was proposed. It is prepared by a one-step, simple continuous, electrospinning process. By adjusting solutions and spinning parameters, the membrane obtains its capillary structure and progressive oleophilicity in one-step preparation. Attractively, the membrane shows separation efficiency and excellent permeability, with a flux of 384801 L m⁻² h⁻¹ bar⁻¹ for the oil-water mixture, and the little water content of less than 18 ppm. And for emulsions, the flux even reaches 50000 L m⁻² h⁻¹ bar⁻¹ and the separation efficiency reaches 99.95%. Furthermore, the membrane has excellent mechanical-stability: at 80 kPa transmembrane pressure, it can still effectively prevent water's penetration. Drawing inspiration from nature, the incorporation of capillary force and progressive wettability-induction force into the separation membrane as an additional dual emulsion separation driving force proves to be a highly effective and versatile approach. This method provides a way to solve the general flux-efficiency balance problem of oil-water separation and also provides a new strategy for the preparation of separation membranes for various purposes.