Aiming at the demand for scientific membrane selection for nanofiltration projects in the field of municipal water supply,18 kinds of commercially available nanofiltration membranes were characterized for their physicochemical properties and evaluated for filtration performance.The results show that the pure water permeance of nanofiltration membranes was mostly 10～20 LMH/bar.There were significant differences between fully aromatic and semi-aromatic polyamide membranes in terms of morphological structure,functional group composition,surface hydrophilicity and pore size distribution.When treating natural water,all nanofiltration mem-branes had a rejection rate of organic matters higher than 70％.Most of the fully aromatic polyam-ide membranes had a high salt rejection(＞90％),while that of the semi-aromatic polyamide mem-branes was basically 20％～60％with a particularly large distinction in hardness ion rejections.For desalination applications such as brackish groundwater treatment,fully aromatic polyamide mem-branes should be selected.To meet the water purification requirements of removing organic mat-ters and preserving inorganic salts,it is recommended to use semi-aromatic polyamide membranes with a molecular weight cutoff of about 330 Da.
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