Investigation of the effect of Ni and Cu variant MOF-74 in the Polydimethylsiloxane (PDMS)-based Mixed Matrix Membranes (MMMs) for efficient gas separation applications.

Abstract

Mixed matrix membranes (MMMs) containing metal-organic frameworks (MOFs) have been an emerging and promising membrane technology to contribute to different gas separation applications including carbon dioxide (CO2) and oxygen (O2) separation, because of their large surface areas and distinctive gas adsorption features. In this work, the fabrication process of Polydimethylsiloxane (PDMS)-based MMMs was reported, in which 0.5 to 2 wt.% of each type of (Cu, Ni)-based MOF-74 variants were incorporated into a PDMS matrix in order to achieve high CO2/N2, O2/N2, and CO2/O2 separation efficiency. These MMMs and their nanofillers (MOF-74) were extensively characterized using scanning electron microscopy (SEM) along with Energy Dispersive X-Ray (EDX) mapping, X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), a single gas permeation testing system, and an ultimate tensile strength testing (UTS) unit in order to gain insight into their properties in relation to their gas separation performance. The 1 wt.% of both (Cu and Ni)-MOF-74@PDMS were selected as the most optimum MMMs due to their uniform morphology and enhanced tensile strength, which exhibited high CO2 permeabilities of 4432 Barrer (37.9% increase) and 4288 Barrer (33.5% increase), respectively. Furthermore, in the case of 1 wt.% Ni-MOF-74@PDMS, the CO2/N2, O2/N2, and CO2/O2 selectivities were also enhanced to 36.2 (141.6% increase), 3.2 (21.9% increase), and 11.25 (98.1% increase), respectively. While, in the case of 1 wt.% Cu-MOF-74@PDMS the CO2/N2 and O2/N2 selectivities showed an increment up-to 94.7 (531.5% increase) and 6.47 (145% increase), respectively, Whereas, at 0.5 wt.%, Cu-MOF-74@PDMS showed the best CO2/O2 selectivity of 25.26 (344.7% increase).