Three-dimensional structure design of tubular polyvinyl chloride hybrid nanofiber membranes for water-in-oil emulsion separation

Abstract

A novel tubular polyvinyl chloride (PVC) hybrid nanofiber membrane with three-dimensional structure interwoven by three-dimensional microspheres and two-dimensional nanofibers was fabricated via electrospinning process, with the polyester (PET) hollow braided tube as the support and hydrophobic nano silica (SiO2) as the inorganic additive. The fabricating strategy was designed as the double-needle electrospinning methods with two-component in respective needles. The synergistic effect of two-dimensional nanofibers interwoven with three-dimensional microspheres endowed the three-dimensional nanofiber membrane with the continuous water-oil-solid interfaces, which slowed down the water wetting process and improved the hydrophobic stability of the membrane. With high porosity and multistage rough structures, the three-dimensional nanofiber membrane could be used as an efficient liquid separation membrane, which had excellent separation efficiency for various surfactant-stabilized water-in-oil emulsions separation without external force. When the SiO2 content reached to 4 wt%, the membrane revealed excellent lipophilicity and superhydrophobicity under oil. Moreover, it produced a high permeation flux up to 358.60 L/m2.h with outstanding separation efficiency more than 95% under the driving of gravity, and the excellent reuse performance in water-in-oil emulsion. In addition, the three-dimensional tubular nanofiber membranes prepared by this method have high porosity, excellent mechanical properties, good thermal stability and hydrophobic stability. This simple, economical and environmentally friendly method provided a convenient and cheap platform for the field of waste oil containing water remediation.