Antifouling slippery liquid-infused membrane for separation of water-in-oil emulsions

To separate water-in-oil emulsions, membranes with super-wetting surface have been developed. However, challenges remain as membrane fouling is unavoidable due to surfactant attachment and pore plugging. Demonstrated here is an antifouling slippery liquid-infused polyethylene terephthalate (SLI-PET) membrane for separation of water-in-oil emulsions. Negatively charged silica nanoparticles (SiNPs) were attached to the aminosilane functionalized PET fiber membrane. The surface energy of the SiNPs-roughened membrane was then lowered by a fluorination process. Types of lubricating oil were poured onto the membrane surface to form the continuous fluid layer. The slippery liquid-infused PET (SLI-PET) membrane can repel various liquids that were immiscible with the infused oil. The SLI-PET membranes infused with oils of low volatility and high viscosity exhibited long-term slippery properties even under evaporation or flowing aqueous immersion. These membranes showed high separation efficiency, excellent antifouling and recyclability in water-in-oil emulsion separation. The oils of high volatility and low viscosity cannot form a stable slippery fluid layer, and only slightly improved the fouling resistance of the membrane.