Tuning the assembly of MgNiO2 nanoparticles-infused polysulfone membranes for efficient gas separation: The selectivity-permeability conundrum

The persistent surge in global energy demand, coupled with escalating environmental apprehensions, has underscored the imperative for adept and sustainable gas separation technologies. Mixed matrix membranes (MMMs) have surfaced as a promising avenue to confront these multifaceted challenges, synergistically harnessing the strengths of conventional polymeric membranes and nanoparticle reinforcements. In this work, MMMs have been tailored for gas separation applications by incorporating MgNiO2 nanoparticles as an additive into the polysulfone (PSf) matrix as they provide additional space (in the form of nanoscale voids) for gas diffusion, facilitating faster gas transport, promoting selective permeation of specific gases, and enhancing membrane stability, in addition to their versatility, ease of preparation, cost-effectiveness and high activity. The crystalline nature of MgNiO2 nanoparticles, as characterized by finely tuned grain sizes, has been validated by powder X-ray diffraction (XRD) analysis. Gas permeation experiments on the developed MMMs encompassing a diverse range of pure gases and gas mixtures have been performed. Among the different MMMs investigated, PSM1 with a composition of 100 mg MgNiO2 nanoparticles has yielded substantial enhancements in permeability and selectivity. The PSM1 membrane exhibits remarkable permeance of 56.9 for H2, 16.3 for CH4, and 15 GPU for CO2, having ideal selectivity ratios of 3.5 and 3.8 for H2/CH4 and H2/CO2, respectively. Finally, this work provides new directions for improving the trade of relationship between the selectivity and permeability of gas mixtures under relevant process conditions.