Pressure-driven water transport behavior and antifouling performance of two-dimensional nanomaterial laminated membranes

Fouling remains a major challenge for the longevity of filtration membranes and their application in membrane-based treatment facilities. Polymers, such as polysulfone (Psf) and polyamide (PA) that are used as commercial and laboratory ultrafiltration and nanofiltration membranes, are prone to severe fouling over the course of their lifetime. In this study, polyethersulfone (PES) membranes were coated with two-dimensional nanomaterials, including graphene oxide (GO), reduced graphene oxide (rGO), and molybdenum disulfide (MoS₂). The effect of the nanosheets on the pressure-driven water transport and antifouling performance of the modified membranes was investigated in terms of water permeability, initial flux decline under simulated fouling condition, and flux recovery ratio (FRR). The GO functionalized membrane significantly impedes water transport due to the side-pinning effect of functional groups. 32% reduction in C–O and 35% reduction in overall oxygen content of GO by reducing thermally it to rGO, restored the permeability by 300%. However, despite the higher initial water flux, the rGO functionalized membranes were still more prone to fouling than GO due to the increase in hydrophobicity. Conversely, MoS₂ nanosheets with no functional groups offer a frictionless water flow through nanochannels. The smooth MoS₂/PES membrane showed better antifouling performance than both the GO and rGO functionalized membranes while providing 3.7 times faster water transport.