In this study, sodium alginate (NaAlg) was grafted with N-vinyl-2-pyrrolidone (NVP) under atmosphere of N-2 with benzophenone. The graft polymerization was carried out by irridiating with UV light. The copolymer was synthesized with the % grafting of 33, by using this copolymer (NaAlg-g-NVP), membranes were prepared and used in the separation of dimethylformamide (DMF) and water mixtures by the pervaporation (PV) method. The effects of the feed composition (0-100 wt%) and operating temperature (30-50 degrees C) on the permeation rate and the separation factor were investigated. Grafting of NVP onto alginate increased the permeation rate whereas decreased the separation factor. NaAlg-g-NVP membranes gave separation factors of 5.6-15.4 permeation rates of 0.96-2.05 kg m(-2) h(-1) depending on the operating temperature and the feed mixture composition. Permeation activation energy of dimethylformamide and water in the pervaporation were calculated as 3.50 kcal/mol and 2.38 kcal/mol, respectively, using an Arrhenius type relationship. In addition sorption-diffusion properties of the NaAlg-g-NVP membranes were investigated at the operating temperature and the feed composition. It was found that the sorption selectivity was dominant factor for the separation of DMF/water mixtures. (C) 2007 Elsevier B.V. All rights reserved.