Pervaporation separation of dimethylformamide/water mixtures through poly(vinyl alcohol)/poly(acrylic acid) blend membranes

Pervaporation performance of crosslinked blend membranes of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAAc) has been attempted for the dehydration of dimethylformamide (DMF). Membranes were characterized by Fourier transform infrared spectroscopy (FT-IR) to assess intermolecular interactions, wide angle X-ray diffractometer (WAXD) to observe the effects of blending on crystallinity, and thermogravimetry (TGA) to study thermal stability. Crosslink density and molar mass between crosslinks of the polymeric membranes were calculated by dynamic mechanical and thermal analyzer (DMTA). Sorption experiments were performed to evaluate the extent of interaction and degree of swelling of the membrane in pure components as well as in mixtures of water and DMF. Membranes were examined for their performance by varying experimental parameters such as operating pressure, membrane thickness, and feed water compositions. The blend membrane enabled a substantial enrichment of water on the permeate side with a moderate increase in selectivity of 275 and a reasonable permeation flux of 0.0125 kg/m(2) h. Membrane selectivities improved with the decreasing feed water concentration, but a simultaneous drop in overall permeation flux was observed. Increasing membrane thickness decreased the flux, whereas higher permeate pressure caused a fall in membrane performance. (C) 2006 Elsevier B.V. All rights reserved.