In this study, Pebax@1657/glycerol/polyethylene glycol 200/iron-nickel oxide quaternary mixed matrix membranes (MMMs) were prepared, to enhance the gas separation permeation of Pebax@1657 copolymer membrane, by utilizing the high miscibility of all the membrane material components and the strong affinity between CO2 and glycerol/polyethylene glycol 200 additives and also with iron-nickel oxide filler. The resultant membranes were examined for CO2/CH4 and CO2/N2 gas separation at 35 ◦C and feed pressures of 2–10 bar. These membranes were also characterized by FTIR-ATR, DSC, FE-SEM, XRD and XRF and the tensile test. Incorporation of these additives in the pure Pebax@1657 membrane significantly improved the separation performance of neat membrane. For example, Pebax@1657/glycerol 15 wt%/PEG 200 20 wt%, containing 3 wt% of NiFe2O4 nanoparticles exhibited the best gas separation performance for CO2/CH4 and CO2/N2 gas pairs. At feed pressure of 10 bar and 35 ◦C, CO2 permeability increased from 148.79 of pristine Pebax@1657 membrane to 269.61 (about 81.2%). CO2/N2 selectivity increased from 40.96 to 273.41 (about 567.5%) and CO2/CH4 selectivity enhanced from 32.11 to 66.17 (about 106%).
