Superwettable Amidoximed Polyacrylonitrile-Based Nanofibrous Nonwovens for Rapid and Highly Efficient Separation of Oil/Water Emulsions

Considering the progressively increasing oily wastewater in the world, the development of energy-saving and environmentally friendly materials with high efficiency and feasible preparation has been of great necessity. In this approach, the amidoximated silicon dioxide/polyacrylonitrile (AO-SiO2/PAN) nanofibrous nonwovens are produced by a combination of electrospinning and electrospraying. A more-porous and higher-roughness skin layer, compared to the pristine PAN nonwovens, is achieved by optimizing the conversion ratio of the nitrile groups during amidoximation. Meanwhile, the obtained nonwovens demonstrate remarkable superhydrophilicity and underwater superoleophobicity, which contributes to its superior oil/water separation performance. With the aid of the ultralow oil adhesion, the underwater oil contact angle (UWOCA) of the nonwovens is nearly 164.1 ± 2°. A high permeation flux of 2846 ± 162 L m–2 h–1 with a separation efficiency over 95.6% for surfactant-stabilized oil-in-water emulsions is achieved under an external pressure of 20 kPa. Moreover, the superior oil resistance of the skin layer endows the modified nonwovens with cycling separation performance, which is promising for applications in the field of oil/water separation.