Superhydrophobic Membrane Fabricated via In Situ Polymerization of Dopamine at the Air–Water Interface for Membrane Distillation with Antiscaling Performance

Membrane distillation (MD)-based seawater desalination has garnered increasing attention in recent years because of its insensitivity to salinity. However, it was limited by salt scaling and membrane wetting due to the complexity of water environments. Herein, an alkali-activated poly(tetrafluoroethylene) (PTFE) membrane surface was functionalized using polydopamine (PDA) via in situ polymerization of dopamine at the air–water interface. Silver nanoparticles (Ag NPs) were further deposited onto the modified PTFE membrane surface by the reduction of silver ions. A superhydrophobic surface with micro-/nanostructures and ultralow surface energy was obtained after continuing to modify with 1H,1H,2H,2H-perfluorodecanethiol. The water contact angle of the superhydrophobic membrane can reach 153.2°. In direct contact MD tests, the superhydrophobic membrane exhibited a stable permeation flux (19.75 kg·m–2·h–1) and excellent salt rejection compared with pure PTFE membrane. Additionally, the superhydrophobic membrane exhibited outstanding antiscaling and antiwetting properties, which considerably extended its service life. Therefore, it can be used as a reference to address salt scaling on the membrane surface.