Bioinspired Dynamic Antifouling of Oil-Water Separation Membrane by Bubble-Mediated Shape Morphing

Oil-water separation membranes easily fail to oil foulants with low surface energy and high viscosity, which severely limits these membranes' applications in treating oily wastewater. Herein, an oil-water separation membrane by bioinspired bubble-mediated antifouling strategy is fabricated via growing hierarchical cobalt phosphide arrays on stainless steel mesh. The as-prepared membrane is superhydrophilic/superaerophobic and electrocatalytic for hydrogen evolution under water, which helps to rapidly generate and release abundant microbubbles surrounding the oil-fouled region on the membrane. These microbubbles can spontaneously coalesce with the oil foulants to increase their buoyancy and warp their interface tension by morphing the oil shape. And this spontaneous coalescence also increases the kinetic energy of oil foulants resulting from the decreased bubbles' interface energy and potential energy. The synergy of the warped interface tension, increased buoyancy, and kinetic energy drives the efficiently dynamic antifouling of this membrane. This dynamic antifouling even can remove some solid sediment such as oily sand particles that causes more serious fouling of the membrane. Thus, this membrane maintains high flux (>11920 L m(-2) h(-1) bar(-1)) in the long-term separation of oil-water and oil-sand-water emulsions by dynamically recovering the decayed flux on demand, which exhibits great potential in treating industrial oily wastewater.

Automated summary

An oil-water separation membrane with bioinspired bubble-mediated antifouling strategy is developed to overcome the limitations of low surface energy and high viscosity of oil foulants. The membrane is superhydrophilic/superaerophobic and can catalyze hydrogen evolution, generating microbubbles that coalesce with the oil fouling and increase their buoyancy and warp their interface tension. The synergy of warped interface tension, increased buoyancy, and kinetic energy enables efficient dynamic antifouling and removal of solid sediment. The membrane maintains high flux in long-term oil-water and oil-sand-water emulsion separation, making it promising for treating industrial oily wastewater.