In-situ incorporating zwitterionic nanocellulose into polyamide nanofiltration membrane towards excellent perm-selectivity and antifouling performances

It remains a huge challenge to develop a high-performance nanofiltration (NF) membrane with excellent permselectivity and antifouling properties. Herein, we report a novel thin-film nanocomposite (TFN) membrane by insitu incorporating zwitterionic nanocellulose during interfacial polymerization. Unlike commonly-used nanomaterials, the zwitterionic nanocellulose anchored with both quaternary ammonium and phosphate group is able to be well dispersible in water to ensure the formation of defect-free separation layer. The resultant membrane exhibited not only increased water permeance (14.4 L m-- 2 h-1 bar- 1) but enhanced divalent salt rejection (RNa2SO4 = 98.3%) owing to the increased surface hydrophilicity and high surface area as well as the extra hydrophilic interfacial nanochannels. With the assistance of high monovalent ion permeability endowed by zwitterions, this TFN membrane also behaved highly efficient antibiotic desalination with elevated separation factor of around 4.3. Moreover, the antifouling capability and cleaning recovery ability was greatly improved when both of the negatively and positively charged bovine serum albumin were utilized as foulants. Under the synergism of nanocellulose and zwitterions, therefore, the developed membrane in this work possessed superior perm-selectivity and antifouling properties, which would have promising potentials in separation fields.