Regulating the interfacial polymerization process for the fabrication of high-performance nanofiltration membranes by using polyethyleneimine-modified mica nanosheets as an interlayer

Nanofiltration (NF) membranes hold considerable promise for desalination and water reuse. However, the trade-off between permeability and selectivity restricted their efficient applications. Herein, we successfully prepared thin-film nanocomposite NF membranes with mica nanosheets interlayer (M-TFNi) by introducing polyethyleneimine-modified mica nanosheets between the porous support layer and the polyamide (PA) layer, which exhibited superior permeance along with high divalent salt rejection. Owing to the “tortuous effect” of PEI-mica nanosheets and hydrogen bonding interactions, the diffusion rate of piperazine (PIP) was slowed down, which resulted in the formation of a thinner and looser PA layer with higher surface roughness and hydrophilicity. The optimized M-TFNi membrane demonstrated an exceptional permeance of 16.24 L m −2  h −1  bar −1 in 1000 ppm Na 2 SO 4 solution at pH of 8 and a high Na 2 SO 4 rejection of 98.8 % at 4 bar, which is enormously higher than that of the pristine NF membrane without the PEI-mica nanosheets as interlayer. Overall, this work devised a new approach to fabricating high-performance NF membranes for efficient water purification.