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-dime thylformamide 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 ca lculated at 25, 35, and 45 degreesC. The Arrhenius activation parameters fo r permeation flux ranged between 22 and 63 kJ/mol, while the activation ene rgy for diffusion ranged between 23 and 67 kJ/mol. Separation selectivity w as between 15 and 22. The highest permeation flux of 0.459 kg m(-2) h(-1) w as obtained for the 93% grafted membrane at 90% of water in the feed mixtur e. The results are discussed using the principles of the solution-diffusion model. (C) 2002 John Wiley & Sons, Inc.