Synthesis and characterization of mixed matrix membranes with graphene oxide-impregnated zeolitic imidazolate framework-8 for enhanced CO2/CH4 separation

For the in situ growth method, the reaction time is important because increasing the reaction time may make it possible for the crystallized ZIF-8 to fully cover the GO sheets; the excess of ZIF-8 particles reduces the aspect ratio of the GO sheet. The reaction time will significantly change the morphology, affecting the composite's ability to absorb selective gas and, in turn, affect the gas selectivity. The present work identifies the reaction time for in situ growth of ZIF-8 nanoparticles on GO sheets. The composite was synthesized at different reaction times of 2, 4, 6, and 8 h and incorporated into the PSF matrix. The fabricated membranes were characterized by FTIR, TGA, SEM, and XRD. The novel synthesized reaction time (6 h) was identified for better enhancement of CO₂/CH₄ separation. For pure gas studies, the results investigated that the CO₂ permeability and CO₂/CH₄ selectivity were increased by 223% and 98%, respectively, compared with plain PSF membrane. In mixed gas (CO₂/CH₄) studies, the CO₂ permeability and CO₂CH₄ selectivity were increased by 349% and 854%, respectively, compared with plain PSF membrane. Hence, the in situ growth method helps synthesize MOF@GO composites in the application of gas separation.