Two-faced channel recovers oil and water from emulsions

Wastewater from many industries, restaurants, and households, contains stable oil-water emulsions that are challenging to break apart. Membranes can do this separation without using chemicals or large amounts of energy. But traditional membranes filter out only oil or water. Now researchers report a simple technique to efficiently recover oil and water at the same time ( Science 2024, DOI: 10.1126/science.adq6329 ). Inspired by the two-faced Roman god Janus , the team at Zhejiang University put a hydrophilic and a hydrophobic membrane next to each other to form a 4 mm-wide channel. As they pump a lab-mixed, surfactant-stabilized, oil-water emulsion into the channel, water quickly passes through the hydrophilic membrane on one side, leaving behind an increasingly oil-rich mix. In the narrow channel, the tiny oil droplets collide and form larger drops, which stick more easily to the hydrophobic membrane and then pass through for collection. The Janus channel setup recovered