A green method to prepare asymmetric positively charged poly(arylene ether sulfone) nanofiltration (NF) membranes was explored by grafting water-soluble poly (ethylene imine) (PEI) onto a poly (arylene ether sulfone) membrane containing tertiary amine groups (PES-TA) and cross-linking with poly(ethylene glycol) diglycidyl ether (PEGDGE). The modifications were shown to increase the positive charge and decrease the pore size of the PES-TA substrate. The optimized NF membrane displayed a pure water flux of 15.5 L m(-2) h(-1). Membrane rejection NaCl, MgCl2, and methyl violet (MV) (at a constant pressure of 4 bar) were measured to be 46.2%, 94.9%, and 99.8%, respectively. Moreover, the membrane maintained excellent chlorine resistance during 100 h of exposure to chlorine. Thus, the membrane shows potential for water desalination and purification applications. (C) 2016 Elsevier B.V. All rights reserved.