Synthesis, characterization and application of crosslinked poly vinyl alcohol membranes for pervaporation and fuel cells

Membranes made by crosslinking poly(vinyl alcohol) (PVA) using glutaraldehyde were tested for dehydration of acetic acid/water mixtures as well as its applicability for direct methanol fuel cell (DMFC) applications. The membranes were extensively characterized before and after crosslinking by FTIR, XRD, SEM, DSC, and tensile testing respectively to verify crosslinking, and observe its effects on intermolecular interactions, crystallinity, surface morphology, temperature resistance and mechanical strength of membranes. The effect of experimental parameters such as feed composition and membrane thickness on separation performance of the crosslinked membranes was determined. Sorption studies were carried out to evaluate the extent of interaction and degree of swelling of the crosslinked PVA membranes (XPVA) in pure as well as binary mixtures of the two liquids. Methanol permeability and proton conductivity were also estimated to check the suitability of this membrane for DMFC applications. Crosslinked PVA membranes were found to have good potential for breaking the azeotrope of 90 wt.% of acetic acid by giving a high selectivity of 111 at a reasonable flux of 0.33 kg/m(2)hr. Separation factor was found to improve with decreasing feed water concentration flux decreased correspondingly. Increasing membrane thickness decreased the flux but had a less profound effect on separation factor. Low methanol permeability, excellent physico-mechanical properties and above all the cost effectiveness could make XPVAs use in DMFC quite attractive.