Biomimetic Janus membrane with unidirectional water transport ability for rapid oil/water separation

Nanoarchitectonics for Electrospun Membranes with Asymmetric Wettability

“…Su et al developed a membrane with hydrophobicity−superhydrophilicity for oil/water mixture separation, which was composed of SiO 2 nanoparticle doped PVDF-HFP nanofibers (PVDF-HFP/SiO 2 ) and superhydrophilic polyamine (PDA) coated Cu@Cu(OH) 2 mesh. 105 Interestingly, this membrane exhibited a high flux of 5305 L m −2 h −1 driven by the Laplace pressure, and the flux remained stable for repeated use for 6 cycle of oil/water separation. According to the directional water transfer principle, Cheng et al proposed an electrospun DCA/PVDF membrane with under-oil superhydrophilicity/ superhydrophobicity for capture water from water-in-oil emulsion.…”

“…One works in the synergistic pattern. The performance for oil–water separation was improved through directional water or oil transport, which is ascribed to the synergistic effect of asymmetric wettability configuration. ,,,− The other one works in the individual pattern. Both oil-in-water (O/W) and water-in-oil (W/O) emulsions can be separated using the same membrane while the surface facing the feed needs to be determined according to the type of the emulsion, which is termed as switchable W/O-O/W emulsion separation. − ,,,,, Wang et al prepared a membrane with asymmetric wettability for oil–water separation by electrospinning, which was composed of poly­(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) and PVDP-HFP comprising uniformly distributed fluorinated decyl polyhedral oligomeric silsesquioxanes (FD-POSS) and fluorinated alkyl silane (FAS) .…”

“…However, the Cu/PVDF membrane was only used to collect a small amount of water droplet from oil. Su et al developed a membrane with hydrophobicity–superhydrophilicity for oil/water mixture separation, which was composed of SiO 2 nanoparticle doped PVDF-HFP nanofibers (PVDF-HFP/SiO 2 ) and superhydrophilic polyamine (PDA) coated Cu@Cu­(OH) 2 mesh . Interestingly, this membrane exhibited a high flux of 5305 L m –2 h –1 driven by the Laplace pressure, and the flux remained stable for repeated use for 6 cycle of oil/water separation.…”

Multi-Bioinspired Janus Copper Mesh for Improved Gravity-Irrelevant Directional Water Droplet and Flow Transport

“…Directional water transportation driven by geometric structures or asymmetric wettability without extra energy consumption is extremely important in efficient transportation and separation processes, including but not limited to fog harvesting and oil/water separation. − Inspired by the Namib desert beetle, cactus, and spider, diverse materials such as fibers or outer surfaces with chemical or structural anisotropy have been fabricated for efficient directional water transport. − In addition to these, guided by the Janus interface of the lotus leaf, Janus porous membranes with asymmetric interfacial wettability have drawn keen interest owing to their unique directional water penetration behavior. − Despite considerable progress, most of these materials generally focus on the relatively large water droplets, which are gravity-dependent. However, for separation and transportation processes, gravity-irrelevant minuscule water droplets and continuous water flow transport are considerably more important.…”

In situ construction strategy for three-dimensional Janus cellulose aerogel with highly efficient oil–water separation performance: from hydrophobicity to asymmetric wettability

“…There have been many reported studies on the surface modification of materials with dopamine, which are mostly based on dopamine oxidative polymerization in an aqueous solution system. 27,28 The required aqueous environment limits dopamine application to hydrolyzable or water-soluble materials, such as polylactic acid-glycolic acid and polyvinyl alcohol, as well as hydrophobic materials.…”