Enhancement CO2 separation performance of three-component pebax-1657-based mixed matrix membranes containing ZIF-67/amine functionalized CNT dual nanofillers

In this study, a novel class of ternary mixed matrix membranes (MMMs) was developed by incorporating dual nanofillers-ZIF-67 and amine-functionalized multi-walled carbon nanotubes (CNT-NH₂)-into a Pebax-1657 polymer matrix to enhance CO₂ separation performance. The dual nanofillers synergistically combine the high porosity and molecular-sieving characteristics of ZIF-67 with the high aspect ratio (~ 250-400) and efficient gas diffusion pathways provided by CNTs, while amine functionalization facilitates strong interfacial compatibility with the polymer matrix. Structural and morphological analyses using FESEM, FTIR, and XRD confirmed uniform nanoparticle dispersion, strong polymer-filler interactions, and preservation of membrane crystallinity. Gas permeation tests revealed substantial enhancements in both CO₂ permeability and selectivity compared to neat Pebax and binary MMMs. The optimal membrane, containing 2 wt% ZIF-67 and 7 wt% CNT-NH₂, exhibited a CO₂ permeability of 82.13 Barrer and a CO₂/N₂ selectivity of 119.76, that exceed Robeson's upper bound. Moreover, the fabricated membranes exhibited excellent stability under elevated feed pressures, underscoring their potential for industrial applications such as flue gas treatment and natural gas purification. These results highlight the effectiveness of dual-nanofiller strategy in addressing traditional limitations of MMMs and offer a promising route toward the development of scalable, high-performance gas separation membranes.