Polyvinyl acetate/titanium dioxide nanocomposite membranes for gas separation

Abstract

Organic–inorganic NCMs were prepared from PVAc and TiO2 using the solution casting method and compared with pure PVAc membranes. The prepared membranes were characterized by optical microscope, FESEM, XRD, DSC, TGA and single gas permeation. FESEM results show that TiO2 particles up to 10wt% are homogenously dispersed and adhered in the PVAc without much aggregation. It was shown by the WAXD results that the crystallinity of PVAc is decreased by the incorporation of TiO2. The addition of TiO2 nanoparticles to PVAc has improved the thermal stability of the resulting NCMs as depicted by an increase in the glass transition temperature (Tg) and the TGA results. Single gas permeation of N2, O2, CO2 and H2 was carried out and the effect of TiO2 loading, feed pressure and operating temperature on the permeability and selectivity of PVAc and PVAc–TiO2 NCMs were investigated. It was found that the addition of TiO2 up to 10wt% has improved both the permeability and selectivity of the NCMs. The permeability of O2, CO2 and H2 was increased by 95%, 79% and 62% respectively. Selectivity of the gas pairs O2/N2, H2/N2, CO2/N2 was also increased by 38%, 26.5% and 14% respectively. Increasing the feed pressure from 2bar to 8bar has no significant effect on the permeability of N2, O2 and H2 resulting in almost unchanged selectivity of the gas pairs O2/N2 and H2/N2. The permeability of CO2 has increased with feed pressure leading to increased and decreased selectivity of the gas pairs CO2/N2 and H2/CO2 respectively. The increase of operating temperature from 30°C to 50°C has a positive effect on the permeation of all gases and a corresponding negative effect on the selectivity of the gas pairs O2/N2, CO2/N2 and H2/N2.