First, a polyethersulfone (PES) membrane was prepared according to the phase inversion technique. Then, chitosan were utilized to fabricate a thin layer on the PES membrane by immersion of the PES membrane into the chitosan solution. After that, the thin layer was modified with acrylamide and microwave irradiation. Finally, the different concentrations of epichlorohydrine (ECH) were utilized to investigate the changes in the thin layer properties. Scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflection-infrared (ATR-IR) apparatus and nanofiltration set-up were used for characterization and investigation of prepared membranes. The results illustrate that the rejection capability and flux of modified membranes have been changed by addition of epichlorohydrine. The pure water flux and Na2SO4 rejection of UF membrane were 170 (L/m(2) h) and 15%, respectively. By fabrication of CS thin layer on the surface of PES support the flux and rejection capability of the membranes were strongly changed. Thin layer composed of 3 wt.% of ECH shows significant Na2SO4 rejection (about 50%) and appropriate flux (30 L/m(2) h), approximately. (C) 2012 Elsevier B.V. All rights reserved.