Efficient oil recovery from emulsions through PDMS decorated nanofibrous membranes via aggregation-release demulsification

Efficient oil/water recovery from emulsions is a challenging task for membrane separation in terms of perm-selectivity and long-term stability. Oil fouling on membrane surface and intrapore disables the efficient recovery of water and oil, limited by size exclusion. Herein, this work proposes an aggregation-release demulsification mechanism to address the fouling issue and achieve efficient oil and water recovery, respectively. Specifically, an ultra-thin sub-10 nm polydimethylsiloxane (PDMS) shell layer was constructed on a hydrophilic polyacrylonitrile (PAN) nanofiber core surface through the hydrolysis and condensation between vinyltriethoxysilane (VTES) and dimethoxydimethylsilane (DMS). The aggregation-release demulsification process on the lipophilic and slippery PDMS surface could be proposed as, oil droplet adsorption, spread out, aggregation and slippery, which vacates the membrane pore space and makes way for water flow. Thus, both purified water and aggregated oil phase could be easily recovered from the permeates. The prepared membrane enabled continuous operation without cleaning. The membrane shows high water permeance (2800 L m-2h−1 bar−1), high emulsion treatment capacity (8000 mL), and high oil (∼85 %) and water (nearly 100 %) recovery. The strategy reported in the current study might offer an opportunity for advancing practical applications of membrane separation for valuable oil products from emulsions.