3D printed robust superhydrophilic and underwater superoleophobic composite membrane for high efficient oil/water separation

The preparation of superhydrophilic and underwater superoleophobic membrane for achieving highly efficient oil/water separation through a facile method is still a great challenge. In this work, a superhydrophilic and underwater superoleophobic membrane with an ordered porous structure is fabricated via a facile direct inkjet writing (DIW) 3D printing technology for the application of oil/water separation. To print the membrane, a solid-like solution containing cellulose acetate (CA), poly (vinyl alcohol) (PVA), and silica nano-particles (SiO2 NPs) is used as the printed ink. As a result, the optimal 3D printed membrane exhibits a quite low water contact angles in-air about 18.14 +/- 2.61 degrees and a high underwater oil contact angle about 159.14 +/- 0.59 degrees, demonstrating its superhydrophilic and underwater superoleophobic characteristics. In oil/water separation process, the optimal printed membrane maintains high oil/water separation efficiency about 99.0% driven by gravity. In contrast to the traditional composite mesh preparing by coating CA/PVA/Si layer on the surface of commercial steel meshes, the printed membrane exhibits superior mechanical stability even after 30 min sonication or 100 bending cycles. Most importantly, the printed membrane still maintains good anti-fouling characteristics and high separation efficiency for separating oil/water mixture after 50 cycles.