Tailoring CO2/N2 separation through multi-filler/Pebax mixed matrix membranes: Roles of activated char, modified perlite, and Mxene

• dual-fillers/Pebax MMM boost CO 2 selectivity and permeability. • The MMMs containing NaEP/AC and AC/MX possess a maximum of 350 Barrer and 73 selectivity. • Hybrid fillers increase the stability, strength, and separation efficiency of the membrane. • Dual-filler approach allows for high-performance, scalable CO 2 /N 2 The development of high-performance membranes for CO 2 /N 2 separation is crucial for greenhouse gas mitigation and industrial gas purification. This work addresses the permeability-selectivity trade-off in conventional polymeric membranes by fabricating Pebax-based mixed matrix membranes (MMMs) incorporating leather-derived activated carbon (AC), sodium hydroxide-modified expanded perlite (NaEP), and MXene (MX) as hybrid organic–inorganic fillers. Systematic gas permeation tests at 35 °C and 2 bar revealed that dual-filler MMMs outperformed both single-filler and neat Pebax membranes. The Pebax/AC/NaEP (1:0.8) membrane achieved the highest CO 2 permeability (350.49 Barrer) and CO 2 /N 2 selectivity (58.52), while Pebax/AC/MX (1:0.8) exhibited exceptional selectivity (73.41) with substantial CO 2 permeability (171.77 Barrer) among the tested compositions. The enhanced performance stems from synergistic effects: AC provides microporous CO 2 -philic sorption sites; NaEP introduces Na + -mediated basicity and improves interfacial compatibility; and MX offers molecular-sieving capability and strong electrostatic interactions with CO 2 . Comprehensive characterization (BET, FESEM, XRD, DSC) confirmed hierarchical porosity, homogeneous filler dispersion, preserved semi-crystallinity, and improved thermal stability. Contact angle and tensile tests further demonstrated increased tunable surface polarity and mechanical robustness. These results verify the synergistic role of organic-inorganic hybrid fillers for the promotion of advanced membrane technology in CO 2 capture with high efficiency and scalability. Notably, the best-performing membranes exceed the 2008 Robeson upper bound and approach the 2019 line for CO 2 /N 2 separation, demonstrating breakthrough performance in overcoming the permeability-selectivity trade-off.