Bioinspired structured superhydrophobic and superoleophilic stainless steel mesh for efficient oil-water separation

• We have prepared a superhydrophobic and superoleophilic stainless steel mesh by a facile immersion process.
• As-prepared surface has a low adhesion property.
• The wettability mechanism relies on micro-nano scale hierarchical structure and chemical component on surface.
• The as-prepared stainless steel mesh has an excellent oil-water separation property after being recycled ten times.

Oily wastewater have caused serious water pollution. The development of effective and cheap oil/water separation materials is urgent for treating this problem. Herein, inspired by superhydrophobic typical plant leaves such as lotus, red rose and marigold, superhydrophobic and superoleophilic stainless steel meshes with excellent oil-water separation efficiency were successfully fabricated by a facile immersion process and then surface modification with stearic acid. The simple immersion process, in which surface roughness and low-surface-energy coating are the two dominant factors of superhydrophobicity, could be accomplished sequentially. It was found that the as-prepared surface is both superhydrophobic and superoleophilic, with the static water angle (WCA) as high as 153 ± 3° and oil contact angle (OCA) of 0°. Furthermore, as-prepared meshes can be applied to separate an oil-and-water mixture bidirectionally and exhibited excellent oil-water separation efficiency including petroleum, toluene, hexane, gasoline and diesel, even after being recycled ten times. Compared with previously reported strategies, this strategy is much easier to carry out and, in the meantime, allows the collection of oil in a continuous manner. This study provides a simple, fast, low cost and environmentally friendly route to fabricate oil-water separation materials as far as large scale manufacturing is considered, which has prospective application in industrial fields such as water treatment and petroleum refining.

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