Robust superhydrophobic carbon nanofiber network inlay-gated mesh for water-in-oil emulsion separation with high flux

Abstract

Much progress has been made toward applying super-wetting membranes to various oil–water separation processes with high molecular permeation flux. However, there are still numerous challenges in the simple preparation of extremely durable membranes with super-wetting properties, especially considering the great developments in high-flux membranes with nanometer-scale thickness. Previous membranes have been usually limited to either high durability with low selectivity or enhanced separation performance with low stability. Herein, an extremely robust carbon nanofiber-polydimethylsiloxane (CNFs-PDMS) network inlay-gated stainless steel mesh (SSM) that shows superhydrophobic and superoleophilic properties is presented. Carbon nanofibers are subtly deposited into SSM pores to form network fillers via an improved vacuum-based filtration. Most importantly, the SSM/CNFs-PDMS membrane exhibits excellent resistance to harsh environmental conditions such as acid, salt, organic, biofouling, and mechanical abrasion. In particular, mechanical damage to the inserted membrane can be avoided using the protective SSM, thereby ensuring super-wetting performance. In the present work, we propose a new concept of discrete or partial superhydrophobicity. Moreover, compared to previous superhydrophobic membranes, the thickness is significantly decreased, leading to enhanced oil-in-water emulsion separation flux. The membranes exhibit a gravity-driven water-in-oil emulsion separation with flux up to 2970 L m⁻² h⁻¹. This work provides a brand new route for designing durable and high-flux separation systems with an inlay-gated structure in the future by combining ultrathin membranes with protective supports.