Preparation of Graphene Based Pebax Composite Membrane and Study on Gas Separation Performance

To improve the CO₂/N₂ separation performance of poly(ether-block-amide) (Pebax) membranes, graphene oxide (GO) was modified with different silane coupling agents. Functionalized graphene oxide (FGO) was then used as a filler to prepare Pebax-based mixed matrix membranes. TEM, SEM, FT-IR, and XRD were used to characterize the modified fillers and composite membranes. The results showed that the silane coupling agents were successfully grafted onto the GO surface. After modification, FGO showed better dispersion in the Pebax matrix than unmodified GO. It also showed better interfacial compatibility with the polymer matrix. The introduction of FGO enhanced the mobility of Pebax chain segments. It also reduced the crystallinity of the membrane and increased its free volume. These changes promoted gas transport and improved both permeability and selectivity. Among all the membranes, Pebax/FGO-KH550 showed the best overall performance. Its tensile strength, elongation at break, and Young's modulus reached (17.83 ± 0.15) MPa, (658.36 ± 0.33)%, and (67.43 ± 0.11) MPa, respectively. These values were 49.58%, 51.97%, and 43.44% higher than those of the neat Pebax membrane. Its CO₂ permeability and CO₂/N₂ selectivity reached 92.53 ± 0.43 Barrer and 49.92 ± 0.91, respectively. These values increased by 41.89% and 52.57%, respectively. The results indicate that KH550-modified GO can effectively improve the structure and separation performance of Pebax mixed matrix membranes. The as-prepared membrane shows good potential for CO₂ separation from flue gas.