Ethylene vinyl acetate/poly(ethylene glycol) blend membranes for CO2/N2 separation

In this paper, novel membranes were prepared from blending the ethylene vinyl acetate (EVA), containing 28 wt.% of vinyl acetate, and poly(ethylene glycol) (PEG) (0-20 wt.%) with molecular weights of 200, 1000, and 1500, and considered for CO2/N-2 separation over the feed pressure of range 2-8 bar. Physical properties and the morphology of the membranes were evaluated by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses in order to justify the gas permeation and separation performance of the membranes. The results showed that CO2 permeability increases by increasing the PEG content of the blend membranes. However, increasing PEG loading enhanced CO2/N-2 selectivity just for the blends containing up to 10 wt.% of PEG and it decreased at higher PEG loadings. The PEG with a molecular weight of 200 showed a more efficient gas separation performance due to its effective role in providing amorphous regions in the blends. Furthermore, higher CO2 permeabilities were obtained at higher feed pressures. The selectivity increased by increasing the feed pressure for neat EVA, EVA/5 wt.% PEG and EVA/10 wt.% PEG membranes, but it had no significant effect on the selectivity of the samples with 15 and 20 wt.% of PEG.(c) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd