Superhydrophobic and superoleophilic nickel foam for oil/water separation

Superhydrophobic and superoleophilic Ni foam was fabricated by immersion coating and drying method. The Ni foam was immersed in a mixture containing polytetratluoroethylene (PTFE) and hydrophobic fumed silica (R805). The mixture was dispersed in a poly(vinylidene fluoride) (PVDF) solution and the PVDF was used as a binder. The as-prepared Ni foam showed superhydrophobic and superoleophilic properties simultaneously and had a water contact angle (WCA) of 155 degrees for water and an oil contact angle (OCA) of 0 degrees for oil. The PTFE-coated Ni foam maintained high separation efficiency after repeated separations (40 times) above 96% for the more viscous olive oil/water mixture and above 99% for the hexane/water mixture. The as-prepared nickel foam proved to be an excellent candidate for the separation of oil and water mixtures.