A novel nanofiltration membrane (PEK-C NF membrane) prepared with poly(amidoamine) (PAMAM) dendrimer and trimesoyl chloride (TMC) by in situ interfacial polymerization on phenolphthalein poly(ether ether ketone) (PEK-C) ultratiltration membrane was investigated. FTIR-ATR, XPS, SEM and contact angle of the water were employed to characterize the chemical and physical changes of resulting membranes. The flux and rejection of resulting membranes increased with increasing concentrations of PAMAM and/or generation numbers of PAMAM for NaCl concentration. Both rejection and flux decrease with an increase of MGSO(4) concentration. The salts rejections order of resulting membrane is MaCl(2) > MaSO(4) > NaCl > NaSO4, which shows that resulting membranes were all positively charged NF membrane. Influences of operating temperature on flux and rejection of different solutes show that resulting membrane is thermostable at higher temperature (e.g. 80 degrees C). The PEK-C NF membrane is especially suitable for separating cationic solutes from others by increasing operating temperature. The pH in the feed increase from 2 to 9 resulted in over two-fold increase in the flux for NaCl solution. Therefore the PEK-C NF membrane is also particularly suitable for treating acidic feed. The studied membrane possesses maximum operating pressure lower than 2.0 MPa and excellent stability during 1080 h (1.5 months) of continuous filtration at 30 degrees C. (c) 2005 Elsevier B.V. All rights reserved.