Highly Hydrophobic and Superoleophilic Nanofibrous Mats with Controllable Pore Sizes for Efficient Oil/Water Separation

Both the wettability and pore size of filtration materials are of great importance in oil/water separation. However, conventional strategies have mainly focused on the fabrication of filtration materials with special wettability, regardless of the pore size. Herein, we demonstrated the design and construction of special wettable nanofibrous mats with tunable pore sizes as filtration materials for selective and efficient separation of oil from oil/water mixtures. The nanofibrous mats with different pore sizes were prepared by the electrospinning approach using a stainless steel wire mesh as the collector, and the results indicated that the pore size of the nanofibrous mats gradually increased with the decrease in the mesh number. The results of the wettability behavior demonstrated that all of the nanofibrous mats showed highly hydrophobic and superoleophilic properties. Owing to the special wettability and the porous structure, the nanofibrous mats were sequentially applied for oil/water separation, and they showed excellent ability to separate both layered oil/water mixture and water-in-oil emulsion; moreover, it was also found that the oil flux could be highly improved by controlling the pore size of the nanofibrous mat and that the oil flux of the nanofibrous mat with the largest pore size was about 10 times higher than that of the conventional nonwoven mat that had the smallest pore size. The nanofibrous mats developed with controllable pore sizes can therefore be practically used as highly efficient filtration materials in the management of oily water.