Fabrication of thin-film composite mixed matrix membrane with 2D magnesium oxide for gas separation application

Abstract

BACKGROUND

Increased concentration of carbon dioxide (CO₂) emission leads to climate change. Hollow-fibre membrane technology seems feasible due to its high packing density, facile processability and easily tuneable properties. A mixed matrix membrane is designed to overcome the balance of solution–dissolution phenomena. However, ensuring optimized dispersion of fillers at the outermost selective skin layer region appears to be challenging. In this study, a thin-film composite mixed matrix membrane (TFCMMM) is fabricated with a facile dip-coating method comprising a PES substrate, polydimethylsiloxane (PDMS) coating layer and magnesium oxide (MgO) nanosheet as the additive filler in the coating layer.

RESULTS

The loading of the MgO nanosheet was varied from 0 to 10 wt% in the PDMS coating solution. Mixed gas performance showed a similar trend to the single gas permeation test, with lower gas permeance and selectivity due to the effect of competitive sorption between the binary gas mixtures. The permeance–selectivity trade-off was absent until the MgO loading of 1.00 wt%, when CO₂/N₂ and CO₂/CH₄ improved by 35.13% and 27.55%, respectively, over pristine TFCMMM. When the MgO loading was increased beyond 2.5 wt%, filler agglomeration and leaching caused the formation of non-selective voids, reducing CO₂/N₂ and CO₂/CH₄ selectivity. The improvement in selectivity observed in this study was due to an increased tortuous pathway of the gas penetrant due to the presence of a high-aspect-ratio MgO nanosheet, resulting in slower diffusion of gas through the PDMS selective layer of the TFCMMM.

CONCLUSION

Our findings provide additional insights into the fabrication of TFCMMM using an MgO nanosheet as an additive filler in the coating layer, specifically for CO₂/N₂ and CO₂/CH₄ separation. © 2025 Society of Chemical Industry (SCI).