Highly efficient quasi-static water desalination using monolayer graphene oxide/titania hybrid laminates

Abstract

By intercalating monolayer titania (TO) nanosheets into graphene oxide (GO) laminates with mild ultraviolet (UV) reduction, the as-prepared RGO/TO hybrid membranes exhibit excellent water desalination performances. Without external hydrostatic pressures, the ion permeations through the RGO/TO hybrid membranes can be reduced to <5% compared with the GO/TO cases, while the water transmembrane permeations, which are measured using an isotope-labeling technique, can be retained up to ~60%. The mechanism for the excellent water desalination performances of the RGO/TO hybrid laminates is discussed, which indicates that the photoreduction of GO by TO is responsible for the effective rejection of ions, while the photoinduced hydrophilic conversion of TO under UV irradiation is responsible for the well-retained water permeabilities. These excellent properties make RGO/TO hybrid membranes favorable for practical water desalination. Excellent water desalination has been achieved using hybrid laminates consisting of graphene oxide and titania. Researchers from Tsinghua University in China and the National Institute for Materials Science in Japan made these hybrid laminates using a simple vacuum filtration method that involves intercalating monolayer titania nanosheets in graphene oxide laminates while employing mild ultraviolet reduction. Employing an isotope labeling technique, they then investigated the water desalination properties of the hybrid laminates. The team ascribed the low ion flow through the hybrid membranes to the photoreduction of graphene oxide by titania, whereas they attributed the high water flow through the membranes to the hydrophilicity of titania, which was induced by ultraviolet irradiation. Such reduced graphene oxide/titania hybrid membranes are very promising for practical water desalination. By intercalating monolayer titania nanosheets (TO) into graphene oxide (GO) laminates, assisted with mild ultraviolet reduction, the as-prepared hybrid membranes exhibit excellent water desalination performances. The photoreduction of GO by TO is responsible for the effective rejection of ions, while the photoinduced hydrophilic conversion of TO is responsible for the well-retained water permeabilities.