Janus Gradient Meshes for Continuous Separation and Collection of Flowing Oils under Water

Gradient meshes with Janus wettabilities are fabricated to stably separate and collect spilled oils from a range of flowing oily wastewater. Here, we demonstrate an overflow with separation methodology, which combines selective oil overflow and membrane separation, to separate low content oils from dynamic flowing oil–water mixtures by a curved gradient mesh that covered on a solid edge. The microscaled air–oil–water–solid four-phase wetting state during the oil–water separation process is visualized and demonstrated. The fundamental understanding of this overflow with separation system and the superior gradient mesh materials would enable us to construct a wide variety of separation devices out of traditional designs and advance related applications, such as wastewater treatment and fuel purification.