Cobweb-Inspired Superhydrophobic Multiscaled Gating Membrane with Embedded Network Structure for Robust Water-in-Oil Emulsion Separation

Abstract

The separation of oil–water mixtures using superwetting membranes is increasingly desired, particularly for the practical processes of environmental protection and industrial production. However, achieving durability and multifunction in current separation systems, among other issues, remains challenging. Herein, a cobweb-inspired gating multiscale pore-based membrane has been created as the framework system for removing emulsified water from an oil phase. This membrane was assembled using macroscale chemically etched stainless steel mesh (ESSM), a microscale network of carbon nanofibers (CNFs), and a nanoscale network of single-walled carbon nanotubes (SWCNTs). Superhydrophobic and superoleophilic interfaces were then fabricated on the ESSM/CNFs–SWCNTs gating membrane using a polydimethylsiloxane (PDMS) coating. The ability of this membrane with a discrete water-repellent property to resist mechanical damage was demonstrated in gravity-driven water-in-oil emulsion separation with high performance; this behavior was attributed to the protective metal mesh and different pore scales resulting from the embedded dual-scale network structure. As a result, this smart superwetting membrane structure can serve as a novel platform for constructing a multifunctional emulsified oil–water separation system with high robustness. Moreover, on the basis of the findings in this study, current filter membranes fabricated using a fibrous network can be improved to achieve higher durability.