Hierarchically structured biomimetic membrane with mechanically/chemically durability and special wettability for highly efficient oil–water separation

Abstract

Membrane-based materials with selective superantiwetting/superwetting surfaces have been applied widely to tackle the concerns of the ever-growing discharge of industrial oily wastewater, as well as frequent oil spill accidents. However, conventional membrane-based separation technologies are inefficient and limited, either by insufficient robustness or by the inadequate anti-oil-fouling property. Herein, a biomimetic superhydrophobic membrane (BSM) with multiscale hierarchical structures (MHSs) was prepared through a method combing self-growth and spray coating. Remarkably, the BSM featured a static water contact angle of 153 ± 0.5°. Accordingly, the BSM possessed highly efficient oil–water separation capability (>95%). In addition, the anti-oil-fouling property and anti-drag capability in the oily seawater of BSM were systematically investigated. In fact, the repellent properties of BSM toward multiple mixtures were attributed to the synergistic effect of both physical structures (biomimetic MHSs) and hydrophobic chemical compositions. Moreover, the BSM demonstrated excellent mechanical robustness (the number of abrasion cycles reached 35) and chemical durability (maintain superhydrophobicity in pH 1–14) through abrasion and strong acid/alkali corrosion tests, respectively. The durability of BSM provided more possibilities for its practical applications. The findings in this work offer a facile yet effective strategy for designing superhydrophobic membranes with excellent physicochemical durability and suggest a great potential value for oil–water separation and drag reduction applications.