Interfacial design of polysulfone/Cu-BTC membrane using [Bmim][Tf2N] and [Dmim][Cl] RTILs for CO2 separation: Performance assessment for single and mixed gas separation

An upsurge in searching membranes with improved perm-selectivity and long-term stability is crucial in membrane-based gas separation. Herein, we engineered the interfacial characteristics of Cu-BTC MOFs with the polysulfone (PSf) matrix using ionic liquids (ILs) at the polymer-filler interface. Two different ILs, [Bmim][Tf2N] and [Dmim][Cl], were used to prepare composite PSf/Cu-BTC/[Bmim][Tf2N] and PSf/Cu-BTC/[Dmim][Cl] membranes. The membranes micro and chemical structures were characterized using XRD, FESEM, and XPS techniques. Results indicated that the multifunctional properties of ILs and Cu-BTC particles influenced the membrane formation mechanism. The uniform dispersion of Cu-BTC filler particles with the inclusion of [Bmim] [Tf2N] and [Dmim][Cl] ILs on the membrane surface was evident from the morphological studies. The absence of a leaky interface by the ILs integration in the PSf/Cu-BTC/[Bmim][Tf2N] and PSf/Cu-BTC/[Dmim][Cl] membranes results in a pronounced increase in selectivities. For instance, PSf/Cu-BTC/[Dmim][Cl] membranes, the CO2 permeance was noticed to be 29.35 +/- 0.35 GPU, and their corresponding gas pair selectivities were noted to be significantly higher than the neat and PSf/Cu-BTC membranes. Similarly, in PSf/Cu-BTC/[Bmim][Tf2N] membrane exhibited optimum CO2 permeance of 30.44 +/- 0.49 GPU with the CO2/N-2 and CO2/CH4 selectivities of 61 and 59.70%, respectively, higher than neat PSf membrane. Furthermore, these membranes showed better anti-aging resistance and long-term stability than the neat PSf membranes. The merits of a simultaneous increase in permeance and selectivities and the good stability and scalable properties make the proposed PSf/Cu-BTC/IL membranes of great interest for the industrial CO2 separation from the gas exhausts.

Automated summary

In this study, the interfacial characteristics of Cu-BTC MOFs with the polysulfone (PSf) matrix were engineered using ionic liquids (ILs), leading to significant improvements in gas separation membranes. The addition of ILs resulted in uniform dispersion of Cu-BTC filler particles and the elimination of leaky interfaces, leading to increased selectivity and stability. The proposed PSf/Cu-BTC/IL membranes have great potential for industrial CO2 separation from gas exhausts.