Graphene oxide interlayered thin-film nanocomposite hollow fiber nanofiltration membranes with enhanced aqueous electrolyte separation performance

In this study, a kind of thin-film nanocomposite (TFN) hollow fiber nanofiltration (NF) membranes was fabricated via incorporating graphene oxide (GO) interlayer using the interfacial polymerization (IP) reaction between piperazine (PIP) and trimesoyl chloride (TMC). The surface morphology and cross-sectional structure of the fabricated TFN hollow fiber NF membrane were extensively investigated. The effects of the PIP concentration, species of the aqueous additives, and the GO loading on the structure and performance of the hollow fiber NF membrane were also investigated in detail and the optimal preparation conditions were achieved. Fourier transform infrared spectroscopy (FTIR) confirmed the successful introduction of the GO interlayer into the composite hollow fiber NF membrane. Moreover, the incorporation of GO interlayer helped to reduce the skin thickness of the composite hollow fiber NF membrane remarkably, and thus helped to increase greatly the water permeance while maintaining a high salt rejection. Under an optimal GO loading of 20.0 mg m(-2), the TFN hollow fiber NF membrane achieved a water permeance of 80 L m(-2) h(-1) MPa-1 and a Na2SO4 rejection of 96.1% for 2000 mg L-1 aqueous Na2SO4 solution, much higher than the interlayer-free thin-film composite (TFC) membrane. Meanwhile, the TFN hollow fiber NF membrane showed an excellent selectivity of Na2SO4 over NaCl, as well as good fouling resistance and long-term stability, demonstrating the vast potential in application for the selective separation of monovalent salt and divalent salt.