Agnps-Thiols Modified Pvdf Electrospun Nanofiber Membrane with a Highly Rough and Ph-Responsive Surface for Controllable Oil/Water Separation

Abstract

To develop a novel membrane with controllable wettability in response to external stimuli for intelligent oil/water separation is always in urgent demand. In this study, a pH-responsive nanofibrous membrane was prepared by the step-by-step modification of polyvinylidene fluoride (PVDF) electrospun nanofiber membrane, including mussel-inspired self-polymerization of polydopamine (PDA), immobilization of silver nanoparticles (AgNPs) and self-assembly of thiols. A rough membrane surface could be formed by the loading of AgNPs, and the subsequent introduction of HS(CH 2 ) 11 CH 3 /HS(CH 2 ) 10 COOH via metal-thiol coordination could endow the membrane with pH-responsive wettability. The surface of the membrane was able to quickly and reversely switch between superhydrophobic and superhydrophilic through simply applying pH stimulus at pH 7 and 13, respectively. The membrane achieved separation efficiency of over 99.2% for light oil/water mixture and 96.5% for heavy oil/water mixture with a stable flux of around 2500 L/m 2 ·h for water and 11296 L/m 2 ·h for oil over 10-cycle separation process. The prepared pH-responsive membrane, with advantages of quick switching rate, good reusability and stability as well as excellent separation performance on both multiphase oil/water mixture and surfactant-stabilized oil-in-water emulsion, could be potentially applied for smart and energy-saving separation and recycle of oil or water from oily wastewater.

Keywords: oil/water separation, pH-responsive membrane, Electrospinning, Surface Modification, Oil-in-water emulsion