Influence of Casting Solvents on CO₂/CH₄ Separation Using Polysulfone Membranes.

Area of Science:

• Materials Science
• Chemical Engineering
• Membrane Technology

Background:

• Polysulfone (PSF) membranes offer high-temperature resistance, low cost, and efficient separation.
• CO2/CH4 separation is crucial, driving demand for advanced membrane materials.
• Solvent selection is critical for tailoring membrane properties and separation efficiency.

Purpose of the Study:

• To evaluate chloroform (CF) and tetrahydrofuran (THF) as solvents for casting polysulfone (PSF) membranes.
• To investigate the CO2/CH4 separation performance of PSF membranes synthesized using CF and THF.
• To analyze the effect of gas pressure (1-10 bar) on membrane permeability and selectivity.

Main Methods:

• Casting of polysulfone (PSF) membranes using two different solvents: chloroform (CF) and tetrahydrofuran (THF).
• Gas separation experiments using a binary mixture of carbon dioxide (CO2) and methane (CH4).
• Evaluation of membrane performance under varying gas pressures from 1 to 10 bar.

Main Results:

• Maximum CO2 permeability of 62.32 barrer (THF) and 57.59 barrer (CF); CH4 permeability of 2.06 barrer (THF) and 2.12 barrer (CF) at low pressures.
• Achieved selectivity values of 48 for THF and 36 for CF at 1 bar.
• Both permeability and selectivity decreased with increasing pressure for both solvents.

Conclusions:

• The solvent used in the in-situ synthesis of polysulfone (PSF) membranes significantly influences CO2/CH4 gas separation.
• PSF membranes cast using THF demonstrated superior performance compared to those cast using CF, exceeding the Robeson upper bound.
• THF is a more advantageous solvent for developing high-performance polysulfone membranes for CO2/CH4 separation.