Superhydrophobic and superoleophilic electrospun nanofibrous membranes exhibiting excellent oil/water separation performance were green fabricated by a facile route combining the amination of electrospun polyacrylonitrile (APAN) nanofibers and immobilization of a Ag nanocluster with an electroless plating technique, followed by n-hexadecyl mercaptan (RSH) surface modification. By introducing the hierarchically rough structures and low surface energy, the pristine superhydrophilic APAN nanofibrous membranes could be endowed with a superhydrophobicity with water contact angle of 171.1 ± 2.3°, a superoleophilicity with oil contact angle of 0° and a self-cleaning surface arising from the extremely low water contact angle hysteresis (3.0 ± 0.6°) and a low water-adhesion property. Surface morphology studies have indicated that the selective wettability of the resultant membranes could be manipulated by tuning the electroless plating time as well as the hierarchical structures. More importantly, the extremely high liquid entry pressure of water (LEPw, 175 ± 3 kPa) and the robust fiber morphology of the APAN immobilized Ag nanocluster endowed the as-prepared membranes with excellent separation capability and stability for oil/water separation by a solely gravity-driven process. The resultant membranes exhibited remarkable separation efficiency in both hyper-saline environment and broad pH range conditions, as well as excellent recyclability, which would make them a promising candidate for industrial oil-contaminated water treatments and marine spilt oil cleanup, and provided a new prospect to achieve functional nanofibrous membranes for oil/water separation.
Keywords: electrospinning; immobilization; nanocluster; oil/water separation; superhydrophobicity.