Enhancing the performance of a modified poly(ether-b-amide) blend membrane by PAMAM dendritic polymer for separation of CO2/CH4

Novel dense membranes were fabricated by blending poly(ether-b-amid), Pebax 1657, as the matrix and a poly (amidoamine) dendritic polymer (PAMAM), as the modifier, to evaluate CO2/CH4 gases separation. The study investigated the effects of PAMAM loading, operating pressure, and temperature on gas permeability and CO2/ CH4 pair-gas ideal selectivity. All the membranes were characterized using various analytical techniques, including ATR-FTIR, XRD, SEM, FESEM, DSC, AFM, Tensile Analysis, density, Aging, Stability pure gas permeation, and gas solubility tests. FTIR results confirmed the interaction of PEO and PA segments with PAMAM increased polymer crystallinity, which is in agreement with DSC, XRD, and Tensile Analysis results. The membrane containing 3 wt% PAMAM showed the highest FFV which along with facilitated transport of CO2 by PAMAM, resulted in the highest CO2 permeability equal to 56.9 Barrer at 2 bar and 30 degrees C (more than 30% higher than the neat Pebax membrane at the same condition). Furthermore, the addition of 1 wt% PAMAM to Pebax increased the CO2/CH4 selectivity to 22.8 at 8 bar and 30 degrees C (more than 78% higher than the neat Pebax membrane at the same condition). Increasing PAMAM loading and applied pressure resulted in the enhancement of gases solubility, and a better ideal selectivity was obtained, correspondingly, Also higher solubility of CO2 compared with CH4 was confirmed by solubility measurements. It was revealed that gas permeability in the membranes was primarily governed by gas solubility rather than diffusivity. The results demonstrate that the modifying Pebax membrane by PAMAM enhances the separation performance with a negligible change against aging and good stability, which confirms potential applications of Pebax/PAMAM membranes in gas separation processes.