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Magnetic-field-induced dispersion of magnetic fillers has been proven to improve the gas separation performance of mixed matrix membranes (MMMs). However, the magnetic field induced is usually in a horizontal or vertical direction. Limited study has been conducted on the effects of alternating magnetic field (AMF) direction towards the dispersion of particles. Thus, this work focuses on the incorporation and dispersion of ferromagnetic iron oxide–titanium (IV) dioxide (αFe2O3/TiO2) particles in a poly (2,6-dimethyl-1,4-phenylene) oxide (PPOdm) membrane via an AMF to investigate its effect on the magnetic filler dispersion and correlation towards gas separation performance. The fillers were incorporated into PPOdm polymer via a spin-coating method at a 1, 3, and 5 wt% filler loading. The MMM with the 3 wt% loading showed the best performance in terms of particle dispersion and gas separation performance. The three MMMs were refabricated in an alternating magnetic field, and the MMM with the 3 wt% loading presented the best performance. The results display an increment in selectivity by 100% and a decrement in CO2 permeability by 97% to an unmagnetized MMM for the 3 wt% loading. The degree of filler dispersion was quantified and measured using Area Disorder of Delaunay Triangulation mapped onto the filler on binarized MMM images. The results indicate that the magnetized MMM presents a greater degree of dispersion than the unmagnetized MMM.

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Mixed matrix membranes (MMMs) separation is a promising technology for gas permeation and separation involving carbon dioxide (CO2). However, finding a suitable type of filler for the formation of defect-free MMMs with enhancement in gas permeability remains a challenge. Current study focuses on synthesis of KIT-6 silica and followed by the incorporation of KIT-6 silica as filler into polysulfone (PSF) polymer matrix to fabricate MMMs, with filler loadings of 0–8 wt %. The effect of KIT-6 incorporation on the properties of the fabricated MMMs was evaluated via different characterization techniques. The MMMs were investigated for gas permeability and selectivity with pressure difference of 5 bar at 25 °C. KIT-6 with typical rock-like morphology was synthesized. Incorporation of 2 wt % of KIT-6 into PSF matrix produced MMMs with no void. When KIT-6 loadings in the MMMs were increased from 0 to 2 wt %, the CO2 permeability increased by ~48%, whereas the ideal CO2/CH4 selectivity remained almost constant. However, when the KIT-6 loading in PSF polymer matrix was more than 2 wt %, the formation of voids in the MMMs increased the CO2 permeability but sacrificed the ideal CO2/CH4 selectivity. In current study, KIT-6 was found to be potential filler for PSF matrix under controlled KIT-6 loading for gas permeation.

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The development of mixed matrix membranes (MMMs) for effective gas separation has been gaining popularity in recent years. The current study aimed at the fabrication of MMMs incorporated with various loadings (0–4 wt%) of functionalized KIT-6 (NH2KIT-6) [KIT: Korea Advanced Institute of Science and Technology] for enhanced gas permeation and separation performance. NH2KIT-6 was characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and N2 adsorption–desorption analysis. The fabricated membranes were subjected to FESEM and FTIR analyses. The effect of NH2KIT-6 loading on the CO2 permeability and ideal CO2/CH4 selectivity of the fabricated membranes were investigated in gas permeation and separation studies. The successfulness of (3-Aminopropyl) triethoxysilane (APTES) functionalization on KIT-6 was confirmed by FTIR analysis. As observed from FESEM images, MMMs with no voids in the matrix were successfully fabricated at a low NH2KIT-6 loading of 0 to 2 wt%. The CO2 permeability and ideal CO2/CH4 selectivity increased when NH2KIT-6 loading was increased from 0 to 2 wt%. However, a further increase in NH2KIT-6 loading beyond 2 wt% led to a drop in ideal CO2/CH4 selectivity. In the current study, a significant increase of about 47% in ideal CO2/CH4 selectivity was achieved by incorporating optimum 2 wt% NH2KIT-6 into the MMMs.

The main obstacle encountered during the development of polyhedral oligomeric silsesquioxane (POSS) mixed matrix membrane (MMM) via physical blending is the combination of compatible inorganic filler and polymeric matrix. In this work, mono-functional POSS of different amine functionalised substituent chain lengths namely aminopropylisobutyl POSS (AMPOSS-a) and aminoethylaminopropylisobutyl POSS (AMPOSS-b) were incorporated into Polysulfone (PSf) membrane at 1wt%, 2wt% and 3wt% loadings. The effect of amine substituent chain lengths on its compatibility and dispersion properties as well as the glass transition temperature of the MMMs were studied using scanning electron microscope (SEM), energy dispersive X-ray (EDX) and differential scanning calorimeter (DSC). Particle agglomerations were observed to increase with the loadings of both fillers although more prominent in AMPOSS-b/PSf membranes. This was attributed to the interparticle forces such as van der Waals and electrostatic forces. Distribution of both fillers were concentrated at the upper region of the membranes at 1wt% and 2wt% as a consequence of their density difference. The glass transition temperature (T g ) for pristine PSf at 197ºC showed an overall decrement between 40.3ºC to 47.1ºC when AMPOSS-a and AMPOSS-b were incorporated. The decrement was due to AMPOSS particle loadings, surface chemistry and particle-polymer chain topology. Hence, mono-substituted POSS with varying amine substituent chain lengths did not improve the glass transition temperature nor contribute to homogeneous MMM morphology. This had been identified to be the consequence of POSS surface energy, which might be caused by the association of hydrocarbon chains saturated on the particle surface due to the presence of isobutyl group.

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