Study On Orderly Stacked Crosslineked Graphene Oxide Composite Membranes And Its Nanofiltration Performance

Nanofiltration(NF)technology is widely recognized and applied because of its high-throughput,high-selectivity,energy-saving,environmentally friendly,easy-to-implement.The nanofiltration membrane is a charged membrane,which relies mainly on size sieving and charge repulsion for selective separation.According to the shortcomings of traditional nanofiltration membrane,such as low flux,poor stability and short lifetime,researchers are looking for a variety of new membrane materials.Graphene oxide(GO),as a new two-dimensional nanomaterial,has excellent mechanical and chemical stability,good antibacterial and anti-pollution ability.The layered structure that stacked on each other,the interstices and defects of the layers are the basis for its application in the field of separation membranes.Furthermore,GO are rich in oxygen-containing functional groups,which are easy to functional modificatedIn this study,GO was first functionalized with cross-linker ethylenediamine(EDA),and then stacked on a dopamine-pretreated three-dimensional tubular ceramic substrate by vacuum-assisted self-assembly technique.EDA can enhance stability when the composite membranes in the aqueous phase while adjusting the interlayer spacing of GO.Scanning electron microscopy(SEM),fourier transform infrared spectrometer(FTIR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),etc.were used to analyze the change of morphology and cross-linking degree.The flux and rejection of the composite membrane for eriochrome black T(EBT)are 181.82 Lm-2h-1MPa-1 and 98.45%,respectively,and the composite membrane can operate stably for 120 h.The membrane fabricating method is improved by using multiple tailored assembly.The deposition speed of membrane-fabricating process is changed from fast to slow,which facilitates the orderly stacking of the nanosheets,greatly reduces the mass transfer resistance,and can synergistically enhanced the nanofiltration performance with EDA.Through the above characterization methods and membrane pore size,contact angle and other analyzers,the regularity change of membranes is characterized.The rejection of the composite membrane to eriochrome black T was 98.60%and the flux improved to 375.75 LM-2hh-1 MPa-1.The flux and rejection of Na2SO4 were 237.72 Lm-2h-1 MPa-1 and 78.32%,respectively.