Novel superhydrophobic nanofibrous membrane grafted with silica nanoparticles for efficient oil/water emulsion...

Separating immiscible oil/water mixtures is relatively straightforward with conventional methods, but emulsions present a greater challenge. Efficient emulsion separation is crucial to preventing oil pollution, driving the need for advanced superhydrophobic and superoleophilic membranes. In this study, we demonstrate a method to adjust the membrane's wettability on a specific side by combining electrospraying and electrospinning techniques. The synthesis process involves electrospraying polystyrene-tetraethyl orthosilicate particles onto a polystyrene membrane, enabling selective tuning of surface wettability on one side. We study the prepared membrane's surface morphology, water contact angle (WCA), permeate flux, and separation efficiency. This hierarchical nanofibrous membrane exhibits a high WCA of ≈ 160 ± 1° and an oil contact angle of 0°. The superhydrophobicity of the membrane enables it to successfully separate oil from diesel, peanut, sunflower, and bean oil/water emulsions, exhibiting an excellent permeate flux of 1935 ± 72 L m^-2 h^-1 and an exceptional separation efficiency of 99 ± 0.2% in the diesel oil/water mixture case. Furthermore, compared to a pristine polystyrene nanofibrous membrane, the composite membrane shows a notable improvement in its oil/water separation performance.