Multi-layer superhydrophobic nickel foam (NF) composite for highly efficient water-in-oil emulsion separation

Taking sponge-like porous nickel foam (NF) with a pore size of about 100 µm as the carrier, superhydrophobic carbon nanoparticles (CNPs) as the filler, and hydrophobic polydimethylsiloxane (PDMS) as the binder, a single-layer superhydrophobic nickel foam composite (NF/CNP-PDMS) is prepared by the simple immersion method. Then the single-layer is laminated into a multi-layer composite with high porosity and micro-nano rough structure for water-in-oil emulsion separation. In addition, in the pressing process, the factors affecting the flux and efficiency of emulsion separation are explored by controlling the areal density and thickness of the three-dimensional multilayer material. As a consequence, the surface of the micro-nano structure has a static water contact angle (WCA) of about 150°. When the areal density is 875 g/m², the thickness is 2 mm, and the efficiency of emulsion separation is as high as 98%. Moreover, the NF/CNP-PDMS has excellent chemical stability, mechanical durability and abrasion resistance, which can be reused for emulsion separation. This work is one of the few experimental schemes using foamed metal for emulsion separation. And the number of pressed layers of nickel foam can be changed to meet different needs of emulsion separation. This work will be beneficial to the research of stable underoil superhydrophobic materials and efficient emulsion separation device.