Magnetic nanoFe2O3 - incorporated PEBA membranes for CO2/CH4 and CO2/N2 separation: experimental study and grand canonical Monte Carlo and molecular dynamics simulations

Mixed matrix membranes (MMMs) comprised of organic selective polymers and inorganic nano-particles under the name of fillers have attracted much attention in the field of gas separation. In this study, poly (amide-6-b-ethylene oxide) [PEBA]/Fe2O3 mixed matrix membranes were prepared using the dry phase separation technique with ethanol / water (70/30 wt%) as solvent. Various amount of Fe2O3 nanoparticles were chosen to disperse within the polymer matrix (0, 0.5, 1, 1.5 and 2 wt% of polymer). To prepare this type of novel membrane, a magnetic field of 0.3 T was used to align the position of NPs. The structural properties and surface morphology of prepared membranes were characterized by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Field emission scanning electron microscopy analysis was also used to study the physical bonding. Phase identification and crystallinity, effective area, and distribution of pore size were investigated by X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. Carbon dioxide permeability through these membranes increased with pressure in the range of 2 to 14 bar. Magnetic membrane loaded with 1.5 wt% of Fe2O3 gave the best performance: CO2 permeability, CO2/CH4, and CO2/N-2 selectivity were enhanced by 30, 42 and 81%, compared to a pure membrane, respectively. The results indicated that the magnetic MMMs gave better separation performance than pure membranes. Molecular simulation has also been used to investigate the structural and transport properties of fabricated membranes. Structural characterizations like radial distribution function (RDF), fractional free volume (FFV), and X-ray diffraction were applied to the simulated membrane cells. Grand canonical Monte Carlo (GCMC) and molecular dynamic (MD) simulations, were used to calculate the selectivity and diffusivity of membranes. Results from experimental tests and simulation runs revealed that the selectivity and permeability of fabricated and simulated membranes are consistent. (c) 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.