A Bioinspired Superwetting Wood-Based Membrane for the Demulsification of Oil-in-Water Emulsions: Sustainable, Naturally Abundant, and High Throughput

Purification of oil-in-water emulsion (OIWE) with high efficiency and environmentally friendly is significant but challenging due to the limitation of oil droplet aggregation and antifouling. In this work, an inverse desert beetle-like material (PDA/ZIF-8@wood membrane) is achieved through the modification of polydopamine (PDA) and the loading of zeolite imidazole framework-8 (ZIF-8) on the delignified wood, which combines abundant porous structure (wood), excellent adhesion (PDA), large specific surface area (ZIF-8), and rich surface functional groups. The unique porous structure of wood ensures the high permeability flux of the emulsion, and hydrophobic/oleophilic ZIF-8 can be used as bumps, which is conducive to capturing and aggregating tiny oil-drops from the OIWE. In addition, the in situ growth method used by the PDA-modified wood surface makes ZIF-8 evenly distributed on the wood surface, enhances the interfacial bonding force between ZIF-8 and wood, and improves the stability and performance of the membrane. The synthesized PDA/ZIF-8@wood membrane can effectively demulsify and aggregate oil droplets to achieve a high efficiency (99.3%) and flux (7407 L m^–2 h^–1 bar^–1) for the OIWE separation. After many cycles, the membrane maintains over a 94.8% retention rate. Its wide source of raw materials, simple synthesis, and high throughput indicate the potential application in the field of OIWE separation.