Graphene oxide (GO) enhanced polyamide (PA) thin-film nanocomposite (TFN) membrane for water purification

• A TFN membrane containing GO nanosheets was prepared by the in-situ IP process.
• GO nanosheets with multiple layer structure and an interlayer spacing around 0.83 nm were prepared.
• Effects of GO concentration on membrane performance were examined.
• Interlayer spacing of nanosheets may serve as water channel and contribute to the permeability enhancement.

A thin-film nanocomposite (TFN) membrane containing graphene oxide (GO) nanosheets was prepared by the in-situ interfacial polymerization process. Aqueous m-phenylenediamine (MPD) and organic trimesoyl chloride (TMC)–GO mixture solutions were used in this process. GO nanosheets with a multilayer structure and an interlayer spacing around 0.83 nm were prepared and used as fillers at concentrations ranging from 0 to 0.02 wt.% during the membrane fabrication. The membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy, and attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy. The membrane performances were evaluated based on water permeability and salt rejection. Results indicated that the GO nanosheets were dispersed well in the polyamide (PA) layer and their incorporation improved membrane performances. With an increasing concentration of GO from 0 to 0.015 wt.% in the TMC-hexane phase during the fabrication, the permeate flux under 300 psi increased from 39.0 ± 1.6 to 59.4 ± 0.4 L/m2 h, while rejections of NaCl and Na2SO4 slightly decreased from 95.7 ± 0.6% to 93.8 ± 0.6% and 98.1 ± 0.4% to 97.3 ± 0.3%, respectively. Interlayer spacing of GO nanosheets may have served as water channels and hence contributed to the water permeability enhancement.

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