GO Framework Membranes with Fine-Tuned Interlayer Channels Via Boron Bridging and Thermal Annealing

A series of boron bridged GO composite membranes have been prepared by deposition of GO boron mixtures on the Torlon® hollow fiber substrates and thermal annealing the resultant membranes. By fine-tuning the interlayer nanochannels of GO layer via different types of boron bridging and thermal annealing, GO framework composite membranes with favourable charge properties and size exclusion functionalities are constructed, allowing fast water permeation with repulsion and blockage of dye molecules. Both pore size distribution and XPS analysis elucidated the evolution of nanochannel sizes and surface chemistry properties in the GO composite membranes annealed under different temperatures. It was discovered that thermal annealing of pristine GO membrane could partially reduce the GO nanosheets and thereby densify the laminate membrane structure. For boron embedded composite membranes, rigid size-defined nanochannels, where maximum water permeability with targeted dye molecular selectivity, could be constructed by manipulating the boron species and annealing temperatures. The newly fabricated membranes exhibited the highest water permeability of 11.66 L m^-2 h^-1 bar^-1 and high rejections toward the testing dyes in a range of molecular weight from 300 Da to 1000 Da. The GO framework membrane may also be potentially employed in the pharmaceutical industry for value-added separation process.