Polydimethylsiloxane/Magnesium Oxide Nanosheet Mixed Matrix Membrane for CO₂ Separation Application

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Rising atmospheric carbon dioxide (CO2) necessitates advanced carbon capture and utilization (CCU) technologies.
• Membrane-based separations offer a promising avenue for efficient CO2 emission reduction.
• Polydimethylsiloxane (PDMS) membranes are explored for CO2 separation applications.

Purpose of the Study:

• To develop and investigate CO2-selective membranes by incorporating magnesium oxide (MgO) nanosheets into a PDMS matrix.
• To determine the optimal loading of MgO nanosheets for enhanced CO2 separation performance.
• To evaluate the effect of MgO nanosheet incorporation on membrane permeability and selectivity.

Main Methods:

• Synthesis of hierarchically two-dimensional (2D) MgO nanosheets with an average thickness of 35.3 ± 1.5 nm.
• Fabrication of mixed matrix membranes (MMMs) by incorporating MgO nanosheets into a PDMS polymer matrix.
• Pure gas permeation experiments were conducted at 2 bar and 25 °C to assess CO2/N2 and CO2/CH4 separation performance.

Main Results:

• Optimal MgO loading was found to be 1 wt.%, showing no significant agglomeration and improving CO2/N2 selectivity from 11.4 to 12.7.
• Higher MgO loading (5 wt.%) led to sedimentation and interfacial defects, increasing CO2 permeability but also enhancing CO2/N2 selectivity to 15.0.
• Membrane performance exhibited minimal pressure dependency, with a linear decrease in CO2 permeability and stable selectivity at varying upstream pressures.

Conclusions:

• Incorporation of MgO nanosheets into PDMS membranes is an effective strategy for enhancing CO2 separation.
• Careful control of filler loading is crucial to prevent agglomeration and interfacial defects, optimizing membrane performance.
• The developed MMMs show potential for efficient CO2 capture applications, with stable performance across a range of operating pressures.