Rolling-Induced Phase Separation: A Dynamic Strategy for High-Performance Oil–Water Emulsion Filtration

This paper presents a strategy for phase-selective separation based on the rolling path of droplets on an inclined functional surface: as a water-in-oil emulsion droplet rolls down an inclined electrospun fibrous slope, the aqueous phase is rapidly absorbed and permeates through the hydrophilic fibrous membrane. The droplet continues rolling, exposing the oil phase, which then proceeds down the incline and into a collective device, thereby achieving oil-water separation from the emulsion. Experimental results show that for 1 μm emulsion droplets, our "inclined filtration" strategy achieves a filtration flux over 4.7 times greater than traditional dead-end filtration under identical conditions. Remarkably, after 50 testing cycles, it maintains a filtration flux more than 10 times higher than the conventional dead-end approach. These features suggest great potential for "inclined filtration" not only in wastewater treatment but also in a broader liquid separation application.