Capillary effect in Janus electrospun nanofiber membrane for oil/water emulsion separation

Abstract

Recently, oil/water separation has become a crucial process due to ever-increasing industrial oily wastewater and frequent oil spill accidents, which have long-term and fatal effects on the ecosystem. Among them, oil/water emulsions, especially for surfactant-stabilized emulsions that contain micro-size droplets (< 20 µm), have been difficult to achieve by conventional separation technologies(Wang et al., 2016). Janus electrospun nanofiber membranes (J-ENMs) have attracted considerable interest as membranes for oil-in-water emulsion separation due to the opposite properties on each side of the membrane(Zhou et al., 2013). Such properties can provide capillary effect and achieve water unidirectional transportation. However, the capillary effect on performances of the J-ENMs is still obscure. Therefore, it is highly important to investigate the relation of pore size, capillary pressure, and fluid flux of them. Therefore, for this study, a series of J-ENMs were facilely fabricated through the sequential electrospinning process with a polystyrene (PS) solution and a polyacrylonitrile (PAN) solution, and detailed investigation of positive and negative capillary pressures on J-ENMs, and the results revealed the significant potential of these membranes for oil-in-water emulsion separation.