A serial wedge-shaped wettability pattern is designed to achieve long-distance spontaneous and directional pumpless transportation of subaqueous gas bubbles.

Oil/water separation has been addressed by various materials characterized with superwettability, but most of the methods involve corrosive or toxic chemicals which will cause environmental concerns. Proposed herein is an environmentally friendly method to realize oil/water separation. Nylon mesh is exposed to atmospheric pressure plasma for surface modification, by which micro-/nanostructures and oxygen-containing groups are created on nylon fibers. Consequently, the functionalized mesh possesses superhydrophilicity in air and thus superoleophobicity underwater. The water prewetted mesh is then used to separate oil/water mixtures with the separation efficiency above 97.5% for various oil/water mixtures. Results also demonstrate that the functionalized nylon mesh has excellent recyclability and durability in terms of oil/water separation. Additionally, polyurethane sponge slice and polyester fabric are also functionalized and employed to separate oil/water mixtures efficiently, demonstrating the wide suitability of this method. This simple, green, and highly efficient method overcomes a nontrivial hurdle for environmentally safe separation of oil/water mixtures and offers insights into the design of advanced materials for practical oil/water separation.

No abstract

Pumpless and directed gas transportation in aqueous environments has promising application prospects in various domains. So far, researches on gas transportation based on superaerophilic channels are limited to the transportation of fewer bubbles with low transportation velocity. How to enhance the transportation velocity and realize the transportation of a large quantity of bubbles (especially for gas jet) for practical applications remain unclear. Here, a half-open wedge-shaped channel with subaqueous superaerophilicity is fabricated, which demonstrates excellent bubble affinity and can realize the pumpless and directed bubble transportation. It is proposed that a Laplace force is the main driving force during the transportation and the magnitude of the force is influenced by both the wedge angle of the channel and geometric parameters of the bubble whereas the direction of the force is determined by the orientation of the channel. By applying a precovered air film on the subaqueous superaerophilic wedge-shaped channel, bubbles demonstrate a higher transportation velocity. Additionally, the prepared channel shows an outstanding affinity to oxygen jet at high flux, which can be utilized to transport oxygen for continuous subaqueous oxygen supplementation.