Thermally evolved and boron bridged graphene oxide (GO) frameworks constructed on microporous hollow fiber substrates for water and organic matters separation

For the first time, ultrathin boron bridged graphene oxide (GO) membranes have been successfully constructed on the modified microporous hollow fiber substrates using borates as the cross-linker. Nanochannels within GO layers can be molecularly engineered by manipulating the annealing process and the chemistry of boron bridges. GO framework composite membranes with proper charge properties and size exclusion functionalities have been developed to allow fast water transport and high rejections. Comparing to the pristine GO membrane, boron bridged GO membranes show not only less variations in terms of flux and rejection with annealing temperature, but also high stability during the long term test. Both pore size distribution and X-ray photoelectron spectroscopy were employed to elucidate the fundamental sciences about the evolution of nanochannels and surface chemistry of GO composite membranes with annealing temperature. The newly fabricated boron bridged GO membranes annealed at 65 °C exhibit a water permeability of 6.64–11.66 L m⁻² h⁻¹ bar⁻¹ and high rejections of >97% against dyes with molecular weights of 300–1000 Da. The boron bridged GO membranes may have great potential to treat hot and harsh wastewater as well as for water reuse and dye separation industries.