Papers by Author: Kueir Rarn Lee

Abstract: This study explored the application of MOF-modified membrane for gas separation. Microporous aluminum fumarate (A520) was used to modify polyimide (PI) membrane using N-methylpyrrolidone (NMP) as solvent. The MOF-modified mixed matrix membrane (MMM) was subjected to gas permeability tests, using gas permeability apparatus (GPA). GPA results showed that adding 10wt% MOF to the membrane increased permeabilities of N₂ and CO₂ gases by up to 34%, and by 19% for O₂ gas, without compromising selectivity. Further increasing MOF loading beyond 10wt% considerably decreased selectivities despite significantly increased permeabilities. Cahn adsorption experiment confirmed and supported this GPA data. These results indicate that MOF were successfully intercalated with the polymer as revealed by scanning electron microscope (SEM) images. Other characterizations like dynamic mechanical analysis (DMA), x-ray diffraction (XRD), and positron annihilation lifetime spectroscopy (PALS) showed that the interface and mechanical properties of the MMM also improved. MOF loading beyond 10wt% revealed aggregations forming non-selective voids that probably caused lowered selectivity.

Abstract: Microporous aluminum fumarate (A520) is one of the very few metal-organic frameworks (MOFs) that have been promoted to the level of commercial applications and has recently been proven to exhibit a rigid character with an accessible permanent porosity. This study explored the maximum loading amount of A520 for mixed matrix membrane (MMM) preparation by blending it with polyimide (PI) using N-methylpyrrolidone (NMP) as solvent, without compromising the membrane integrity. Scanning electron microscope (SEM) images revealed that MOFs were able to infiltrate the pores and structures of the polymer, improving the interface and mechanical properties of the polymer, as supported by different characterizations like dynamic mechanical analysis (DMA), x-ray diffraction (XRD), and positron annihilation lifetime spectroscopy (PALS). Results showed that MOF loading beyond 10wt% revealed aggregations that compromised the integrity of the membrane.

Abstract: Positron and Positronium chemistry has been pursued and advanced by many scientists and engineers in both fundamental understanding of Positronium atom and its applications to chemical and polymeric systems during the last decade. This paper presents our recent results from collaborative investigations of positron annihilation in polymeric membranes. Future perspectives of applying Positronium chemistry to membrane science and technology and other related disciplines of nanotechnology, chemical engineering, materials science, energy research, molecules with positrons, biological and medical sciences appear to be promising.