Non-swelling graphene oxide-polymer nanocomposite membrane for reverse osmosis desalination

Although pristine graphene oxide (GO)-based membranes have previously demonstrated promising molecular separation due to their well-defined interlayer spacing, their applications in water processing operations remain limited due to the natural swelling tendency of GO in the aqueous phase which decreases separation ability. In this work, pristine GO laminate has been successfully integrated into a highly crosslinked network to produce membranes with anti-swelling behaviour and excellent desalination capability. The process of free-radical polymerisation in aqueous conditions of a GO suspension enables the formation of a GO-polymer network without covalent bonding between GO and polymer, leading to a combination of mechanical robustness, remarkable water transport properties, and an anti-swelling tendency suitable for the high-pressure operation required for reverse osmosis (RO) membrane process. The resulting GO-polymer membrane was not swollen during RO operation while it was stable under a harsh oxidising environment. It also demonstrated water flux of 33.5 L m−2 h−1 with 98.5% NaCl rejection at 10 bar when prepared by high-vacuum filtration and subsequent polymerisation of the precursor solution on to a mesoporous substrate. This methodology makes large-scalable membrane fabrication very feasible.