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

Abstract

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.