Superior interfacial design in ternary mixed matrix membranes to enhance the CO2 separation performance

Abstract The design of high performance mixed matrix membranes (MMMs) with new chemistry was the main challenge of membranologists in recent years. In this paper, extra high-performance MMMs were fabricated by incorporating the nickel zinc iron oxide nanoparticles and 1-Methyl-3-Octylimidazolium Hexafluorophosphate ionic liquid simultaneously into the Pebax®1657 polymer matrix. The influence of operating pressure (2–10 bar), IL blending (2–8 wt.%), and filler loading (0.5–2 wt.%) on gas permeation properties of each of prepared blend and ternary MMMs were investigated at 35 °C. Moreover, prepared membranes were evaluated by SEM, EDX, FTIR-ATR, DSC, XRD and Tensile analyses. Results showed that the membrane containing 6.5 wt.% ionic liquid and 1.5 wt.% nanoparticle was the optimum. Indeed, a superior combination of Ni2+, Zn2+ and Fe3+ in NiZnFe4O4 as a filler and a unique ionic liquid [OMIM][PF6] with superior CO2 solubility caused an excellent interfacial design and compatibility in MMM structure, which was very effective on gas transport results and mechanical properties of fabricated MMMs. Comparing the results with the pristine membrane, CO2 permeability of the optimum membrane was 300 Barrer (with more than 145% improvement) at 10 bar while the CO2/CH4 and CO2/N2 selectivities were 97.5 (with 369% improvement) and 248.6 (with 281% improvement), respectively. Finally, it was concluded that the fabricated membranes was easily surpassed the Robeson upper bound.