(524c) Nature-Inspired Graphene Oxide Membrane with Vertical Pores for Fast Water Treatment

Due to its green, energy-saving and continuous operation features, membrane technology could improve production of clean, fresh water. Graphene oxide (GO), bearing one carbon atom thickness and various oxidative groups, has become a popular membrane material, owing to its unique features, such as excellent mechanical strength, high surface area and flexibility, low friction for water and CO₂ transport, and the possibility of large-scale production. After its first report in 2007, GO-based membranes have drawn extraordinary attention for applications spanning from desalination to oil/water separation. This is because GO-based membranes possess a tuneable interlayer distance, which allows the selective passage of molecular or ionic species. However, every molecule that travels through GO-based membranes should bypass the GO nanosheets, which increases the mass transfer pathway and decreases the permeate flux. Herein, GO membranes with vertical pores are fabricated by using anodic aluminum oxide (AAO) membrane as template and etching with O₂ plasma. Such membranes possess short water transfer channels for water transport and, meanwhile, the hydroxyl groups formed by O₂ plasma could bond water molecules and generate a hydration layer on the membrane surface. The latter improves their antifouling properties, which is inspired by the structure of sugars on cell membranes, taking advantage of the hydration layer effect and steric hindrance effect to prevent foulants from adhering on the membrane surface. By controlling the etching time of the O₂ plasma, the pore size of the GO membrane is changed from 0.8 nm (the interlayer spacing) to 200 nm, which can be used in different fields for water treatment. This study may offer a simple and versatile approach to regulate the pore size of GO-based membranes with improved antifouling properties over a wide range of operating conditions.