A modified thin film composite nanofiltration (TFC/NF) membrane was prepared by interfacial polymerization between piperazine and trimesoyl chloride monomers and NH2 functionalized multiwalled carbon nanotube (NH2-MWCNT) as a hydrophilic modifier. The surface morphology and hydrophilicity of the prepared NF membranes were studied by scanning electron microscopy (SEM) and water contact angle measurements, respectively. These analyses showed the higher hydrophilicity and the smoother surface of the modified membranes. Also, the separation performance of the membranes was investigated using 2000 mg/L of Na2SO4 and NaCl solutions tested by cross-flow filtration system. The NF membrane modified with 0.005 wt NH2-MWCNT presented the best separation performance, including 36.71 and 95.72% rejection of Na2SO4 and NaCl salts, respectively. The fouling resistance of the membranes was also studied using bovine serum albumin (BSA) protein as a model fouling agent, based on the water flux decline during the filtration process. Results showed that the membranes containing NH2-MWCNT in the polyamide layer have improved fouling resistance compared to the unmodified NF. (C) 2016 Elsevier B.V. All rights reserved.