An integrated Janus porous membrane with controllable under-oil directional water transport and fluid gating property for oil/water emulsion separation

Superwetting surfaces have recently attracted extensive attention in oil−water emulsion separation and droplet manipulations, which are widely used in various situations ranging from wastewater treatment, to flexible electronics, to biochemical diagnosis. However, it still remains challenging to obtain asymmetric materials with high efficiency during oil−water separation. Meanwhile, excellent robustness of the superhydrophobic surface is of significance but retards the mobility of droplets due to increased lateral adhesion of small spacing between solid protrusions. Herein, a facile approach is demonstrated to obtain the excellent robustness of Janus fabrics with asymmetric wettability. As for one side of water-inoil emulsion separation, mimicking the soft earthworm with periodically wrinkled skin, an adaptive superhydrophobic fabric was fabricated by wrapping soft wrinkled poly(dimethylsiloxane) (PDMS) polymer with a cross-linking structure on woven fabric fibers induced by Ar plasma treatment. In addition, inspired by the desert beetle's structure but with reversed wettability, the other side of the Janus fabric was constructed for treating emulsion of oil-in-water. In addition, the underwater superoleophobic surface consisting of magnetically responsive PDMS microcilia with slippery heads, which shows robustness against pH, improved water drop mobility and lowered the resistance of fluid friction similar to the intrinsic hydrophobic Salvinia molesta with additional slippery performance. Hence, we propose a novel and easy approach that optimizes enhanced emulsion separation and reduced fluid drag properties simultaneously, which actively broadens their widespread applications.

Section: ■ Introductionmentioning

confidence: 99%

Janus Fabric with Asymmetric Wettability for Switchable Emulsion Separation and Controllable Droplets with Low Friction

Huang

et al. 2023

“…Here, CMC also acted as a binder, which improved the binding force between PDA@ZIF-8 and PTFE obviously. The designed coating membrane with a suitable pore size is an essential and important condition for realizing the rapid and effective separation of oil/water emulsions. − Fortunately, the uniform coating of ZIF-8 and CMC on the surface of the PTFE membrane further reduces the pore size of the pristine PTFE membrane. Thus, the as-prepared membrane can be applied for the successful separation of a range of oil-in-water emulsions, even including the high-viscosity crude oil/water emulsion with a separation efficiency higher than 99.2% and a permeation flux higher than 1306.5 L m –2 h –1 .…”

Section: Introductionmentioning

confidence: 99%

Green Preparation of a Carboxymethyl Cellulose-Coated Membrane for Highly Efficient Separation of Crude Oil-In-Water Emulsions

Sun

Xiang

et al. 2022

Developing high-performance membranes is an extremely significant strategy to combat increasing severe oil pollution. However, most of the previously reported superwettable membranes have been inevitably involved with the use of toxic solvents and complicated preparation processes. In addition, most of them lacked the capacity of separating crude oil-in-water emulsions. Herein, a facile and green strategy is employed to fabricate a polytetrafluoroethylene (PTFE) membrane with a mixed suspension of PDA@ZIF-8 and carboxymethyl cellulose (CMC) using water as a solvent via the vacuum filtration method.

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Yang

et al. 2022

Self Cite

A conceptually novel multi-bioinspired strategy based on structures and functions derived from the Namib desert beetle and lotus leaf is proposed in this paper. The proposed scheme synergistically combines the features of alternating wettability patterns and asymmetric wettability for improved directional water transport. Consequently, a Janus copper mesh, which substantially outperforms other single-bioinspired synthetic materials, is produced. The Janus copper mesh achieves directional self-transportation of tiny water droplets and continuous water flow in a gravity-irrelevant or an anti-gravity manner without energy consumption. This depends on the asymmetric wettability and alternating hydrophobic-hydrophilic wettability patterns on the hydrophobic surface of the mesh. In particular, Janus copper shows remarkable selective directional water transport in a water−oil system, rendering it a promising candidate for practical applications.