Photothermal responsive liquid-filled membrane with anti-fouling properties for oil/water separation

Membranes have been widely used in oil/water separation due to their high efficiency, convenient operation and low cost. However, poor fluidity of viscous oil and membrane fouling remain challenges for efficient oil/water separation using membranes. This study proposes a "two-in-one" design strategy that integrates photothermal properties and liquid-filled slippery surface into a porous membrane, aiming to address these issues. The photothermal responsive liquid-filled membrane is prepared by sequentially depositing silver nanoparticles (Ag NPs), hydrophobic modification with octadecanethiol (ODT), and filling with castor oil, on the polyethersulfone (PES) porous membrane. Under irradiation, the photothermal effect of the Ag NPs layer causes a surface temperature rise, leading to more slippery surface formed by the filled oil layer that is stably locked in the rough nanostructured underlayer; in oil/water separation, the membrane shows significantly improved oil flux, separation efficiency and fouling resistance due to the decreased oil viscosity and the excellent water repellency of the slippery liquid layer. After 10 cycles, the separation efficiency remains above 93.0%. The membrane also has perfect photothermal antibacterial and anti-biological adhesion properties. This multifunctional membrane has important prospects in the recovery of viscous oil from the ocean or wastewater and the development of energy-saving materials.