Ultrapermeable polyamide nanofiltration membrane formed on a self-constructed cellulose nanofibers interlayer

[Display omitted] •TFC-PA NF membrane with in-situ formed cellulose nanofibers as interlayer is prepared via interfacial polymerization.•The membrane exhibits a pure water permeance up to 35.7 Lm−2 h−1 bar−1 and a high Na2SO4 rejection >97%.•The membrane shows a high stability to applied pressure and long filtration time.•The membrane shows an obvious improvement of antifouling performance. Improving the water permeance of polyamide nanofiltration (NF) membranes without the simultaneous loss of rejection is highly desired but remains a challenge. In this work, we prepared an ultrapermeable polyamide NF membrane containing an in-situ-formed cellulose nanofibre (CN) interconnected network film between a polyamide active layer and ultrafiltration (UF) membrane support through direct addition of the CN to a piperazine aqueous solution for interfacial polymerization. Such in-situ-formed CN interlayer with high porosity can provide a large number of channels for water transport. Compared with the polyamide active layer directly supported by the UF support, the polyamide active layer supported by the CN interlayer can contribute a more effective area for water permeation. Consequently, the polyamide NF membrane exhibited a pure water permeance up to 35.7 L m−2 h−1 bar−1 while maintaining salt rejection to Na2SO4 of >97%. This permeance is 2.5 times greater than that of the membrane without the CN interlayer.