Synthesis Of Hydrophobic And Oleophilic Silica Nanofiborous Membranes For Emulsified Oil/Water Separation

Oil-water separation is a worldwide challenge due to the increasing amounts of industrial oily wastewater and polluted oceanic waters, as well as frequent oil spill accidents. Look for the right methods to solve the problem of oil/water pollution, such as recycled and purified pharmaceutical, not only saving energy but also protecting the environment. Membrane separation technology has a broad application prospect in large-scale processing oil-water emulsion pollutants direction because of the small device, easy operation, low energy consumption, highly automated separation process and less chemical additive usage. Electrospinning has gained increasing appeal as a versatile technique that creates various nanofibrous membranes. Inorganic nanofibrous membranes have outstanding performance, such as high temperature resistance, light weight, high strength, good insulation, chemical stability, long service life, due to the applications in high-temperature, self-cleaning areas and so on. The research on hydrophobic and oleophilic inorganic nanofibrous membranes apply to oil/water emulsion separation.In this paper, we firstly utilized electrospinning technic to fabricate superhydrophobic silica nanofibrous membranes. The raw materials we used during fabrication are tetraethyl orthosilicate as silicon source, polyvinyl alcohol as polymer carrier. Combined with sol-gel method and calcined technique, we successfully fabricated flexible silica nanofibers. Then we created hydrophobic and oleophilic silica nanofibrous membranes exhibiting robust thermal stability by a facile combination of electrospun silica nanofibers and a novel in situ polymerized fluorinated polybenzoxazine (F-PBZ) functional layer that incorporated Al2O3nanoparticles (Al2O3NPs). By employing the1wt%F-PBZ and1wt%Al2O3NPs modification, the pristine hydrophilic silica nanofibrous membranes were endowed with a super-hydrophobicity with WCA up to161°and the sliding angle of3°. Furthermore, the as-prepared membranes exhibited high thermal stability (450℃) and excellent stability over a wide range of pH conditions. What is more, the oil contact angle (OCA) decreased from23°to0°, are typical high temperature resistant hydrophobic and oleophilic nanofibrous materials.Meanwhile, surface morphological studies have revealed that the hydrophobic and oleophilic of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Physical techniques are used to confirm the hierarchical structure of F-PBZ/Al2O3NPs modified silica membranes. Cassie theories are also applied to analyze the results of the wetting properties and the f2value of the rough surface is calculated to be0.94.In addition, only driven by gravity the hydrophobic and oleophilic of resultant membranes exhibit an extremely high flux of892Lm-2h-1for effective separation of water-in-oil microemulsions, which is several times higher than those of commercial filtration membranes driven by external pressure and reported materials with similar permeation properties, as well as good antifouling properties and are easily recyclable, thus the new hydrophobic and oleophilic silica nanofibrous membranes have wide application prospect in the field of emulsified oil/water separation.