Improving the permeance of the polyamide (PA) membrane
while maintaining
the rejection is crucial for promoting the development of membrane
separation technology in the practical water-treatment industry. Herein,
a novel metal–ionic liquid (Zn–IL) coordination compound
was synthesized by in situ growth to improve the water permeance of
PA nanofiltration membranes, using an amine-functionalized IL (1-aminopropyl-3-methylimidazolium
chloride, [AEMIm][Cl]) as a ligand to react with Zn(NO3)2·6H2O. Piperazine (PIP) and trimesoyl
chloride (TMC) were adopted to prepare the PA layer covering the Zn–IL
complex. Due to the unique property of the Zn–IL complex, the
Zn–IL/PIP–TMC absorbing force to water was increased,
enabling the fast transport of water molecules through the membrane
pore channels in the form of free water. The resulting Zn–IL/PIP–TMC
nanocomposite membrane exhibited a high permeance of up to 26.5 L
m–2 h–1 bar–1, which is 3 times that of the PIP–TMC membrane (8.8 L m–2 h–1 bar–1), combined
with rejection above 99% for dyes such as methyl blue.