Pervaporation separation of water/dimethylformamide mixtures using poly(vinyl alcohol)-g-polyacrylamide copolymeric membranes

Grafted copolymeric membranes of poly(vinyl alcohol) with acrylamide (PVA-g-AAm) were developed and used in the pervaporation separation of water-dimethylformamide mixtures by varying the amount of water in the feed from 0 to 100%. From these data, the permeation flux, pervaporation separation index, diffusion coefficient, swelling index, and separation selectivity were calculated at 25, 35, and 45 degreesC. The Arrhenius activation parameters for permeation flux ranged between 22 and 63 kJ/mol, while the activation energy for diffusion ranged between 23 and 67 kJ/mol. Separation selectivity was between 15 and 22. The highest permeation flux of 0.459 kg m(-2) h(-1) was obtained for the 93% grafted membrane at 90% of water in the feed mixture. The results are discussed using the principles of the solution-diffusion model. (C) 2002 John Wiley & Sons, Inc.