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Design of niobate nanosheet-graphene oxide composite nanofiltration membranes with improved permeability

Kunimatsu, Misato, Nakagawa, Keizo, Yoshioka, Tomohisa, Shintani, Takuji, Yasui, Tomoki, Kamio, Eiji, Tsang, Shik Chi Edman, Li, Jianxin, Matsuyama, Hideto
Journal of membrane science 2019
asymmetric membranes, dyes, nanofiltration, nanosheets, permeability, sodium sulfate
Membranes assembled by two-dimensional (2D) nanosheets have high potential for advanced molecular separation. The intercalation of nanomaterials into the laminar membrane is a promising strategy to control the nanochannel structure. We present 2D niobate nanosheet (NbN)-Graphene oxide (GO) composite membranes fabricated by simple vacuum filtration. The effect of the weight ratio of NbN/GO on the membrane structures and performances is investigated. The NbN-rich membranes have a more stable structure in the wet condition and a membrane structure with a larger channel size compared with GO-rich membranes. Especially, NbN55-GO45 (weight ratio of NbN/GO = 55/45) shows a superior water permeability of 20 L m−2 h−1 bar−1, which is around 6 times higher than an NbN membrane (NbN100) and 2 times higher than a GO membrane (GO100), while maintaining good rejection abilities of an anionic dye (nearly 100% for Evans blue) and salt (60% for Na2SO4). Different models for the water pathway through nanochannels can be classified according to the composite ratio of the NbN-GO membranes.