Engineering environmentally friendly nanofiber membranes with superhydrophobic surface and intrapore interfaces for ultrafast Oil-water separation

Superhydrophobic membranes are energy-efficient for oil–water separation, however, lack of effective approach to develop such membranes hampering their worldwide application of the superhydrophobic membranes. Herein, we provided a facile approach to develop superhydrophobic polylactic acid (PLA) nanofiber membranes through constructing nanoscale fluorine modified SiO2 (F-SiO2) clusters and introducing polydimethylsiloxane (PDMS) coatings by coaxial electrospinning technology. By adjusting the process of the phase inversion of the doping solutions under high voltage during the coaxial electro-spinning technology, the diameter of the PLA based nanofiber and the mean effective pore size of the nanofiber membranes could be finely tailored. F-SiO2 clusters were partly embedded in the nanofiber, increasing nanoscale convex structure further. Moreover, the surface of PLA nanofiber fully covered by the low surface energy coatings, improving the superhydrophobicity of the whole nanofiber membranes. As a result, the membrane surface and the intrapore interface showed excellent hydrophobic properties providing strong repulsion towards water droplets. The modified membranes could remove 100% water droplets with size larger than 150 nm, and demonstrated 98.4% permeance recovery rate. Most interestingly, the permeance (13818.8 L·m−2·h−1·bar−1) of modified superhydrophobic PLA nanofiber membranes were about 110% higher than that of pristine PLA nanofiber membranes, which surpassed that of the most advanced separation membranes reported recently, showing broad application prospect in oil dehydrating from water-in-oil emulsions.