Hongsik Byun

Electrospun nanofiber membranes derived from polyketone (PK) are precisely fabricated to exhibit an excellent separation efficiency for oil/water emulsions. The fiber diameter and pore size of the membrane are controlled by introducing NaOH to the precursor solution prior to electrospinning. The surface properties of the nanofibers are then controlled by the removal of NaOH with water and reduction of functional groups with sodium borohydride (NaBH 4 ) to exhibit an air‐water superhydrophilicity and underwater superoleophobicity. This surface conversion process is easily monitored by the water contact angle and the underwater oil contact angle. Oil/water emulsions, including toluene, soybean oil, and hexadecane are filtered through the membranes to examine their separation efficiency and flux using total organic carbon and UV‐Vis measurements. The optimized membrane exhibits the minimum 97 % separation efficiency for all three oil/water emulsions and recyclability without notably losing its flux under gravity‐driven filtration conditions.