Molecular level understanding of CO2 capture in ionic liquid/polyimide composite membrane

Preparation of Polyimide/Ionic Liquid Hybrid Membrane for CO2/CH4 Separation

Imidazole ionic liquids (ILs) have good affinity and good solubility for carbon dioxide (CO2). Such ionic liquids, combined with polyimide membrane materials, can solve the problem that, today, CO2 is difficult to separate and recover. In this study, the ionic liquid (IL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (IL1), 1-pentyl-3-methylimidazolium tetrafluoroborate (IL2), 1-octyl-3-methylimidazolium tetrafluoroborate (IL3), and 1-dodecylimidazolium tetrafluoroborate (IL4) with different contents were added to a polyimide matrix, and a series of polyimide membranes blended with ionic liquid were prepared using a high-speed mixer. The mechanical properties and gas separation permeability of the membranes were investigated. Among them, the selectivity of the PI/IL3 membrane for CO2/CH4 was 180.55, which was 2.5 times higher than the PI membrane, and its CO2 permeability was 16.25 Barrer, which exceeded the Robeson curve in 2008; the separation performance of the membrane was the best in this work.

The Effect of Complex Modifier Consisting of Star Macromolecules and Ionic Liquid on Structure and Gas Separation of Polyamide Membrane

A novel hybrid membrane was developed on the basis of poly(m-phenylene isophthalamide) (PA) by introducing an original complex modifier into the polymer; this modifier consisted of equal amounts of heteroarm star macromolecules with a fullerene C₆₀ core (HSM) and the ionic liquid [BMIM][Tf₂N] (IL). The effect of the (HSM:IL) complex modifier on characteristics of the PA membrane was evaluated using physical, mechanical, thermal, and gas separation techniques. The structure of the PA/(HSM:IL) membrane was studied by scanning electron microscopy (SEM). Gas transport properties were determined by measuring He, O₂, N₂, and CO₂ permeation through the membranes based on PA and its composites containing a 5 wt% modifier. The permeability coefficients of all gases through the hybrid membranes were lower than the corresponding parameters for the unmodified membrane, whereas the ideal selectivity in the separation of He/N₂, CO₂/N_2, and O₂/N₂ gas pairs was higher for the hybrid membrane. The position of the PA/(HSM:IL) membrane on the Robeson's diagram for the O₂/N₂ gas pair is discussed.

A systematic review of the molecular simulation of hybrid membranes for performance enhancements and contaminant removals

Number of research on molecular simulation and design has emerged recently but there is currently a lack of review to present these studies in an organized manner to highlight the advances and feasibility. This paper aims to review the development, structural, physical properties and separation performance of hybrid membranes using molecular simulation approach. The hybrid membranes under review include ionic liquid membrane, mixed matrix membrane, and functionalized hybrid membrane for understanding of the transport mechanism of molecules through the different structures. The understanding of molecular interactions, and alteration of pore sizes and transport channels at atomistic level post incorporation of different components in hybrid membranes posing impact to the selective transport of desired molecules are also covered. Incorporation of molecular simulation of hybrid membrane in related fields such as carbon dioxide (CO₂) removal, wastewater treatment, and desalination are also reviewed. Despite the limitations of current molecular simulation methodologies, i.e., not being able to simulate the membrane operation at the actual macroscale in processing plants, it is still able to demonstrate promising results in capturing molecule behaviours of penetrants and membranes at full atomic details with acceptable separation performance accuracy. From the review, it was found that the best performing ionic liquid membrane, mixed matrix membrane and functionalized hybrid membrane can enhance the performance of pristine membrane by 4 folds, 2.9 folds and 3.3 folds, respectively. The future prospects of molecular simulation in hybrid membranes are also presented. This review could provide understanding to the current advancement of molecular simulation approach in hybrid membranes separation. This could also provide a guideline to apply molecular simulation in the related sectors.

Experimental study of carbon dioxide absorption by Fe2O3@glutamine/NMP nanofluid

In this study, for the first time, the nanoparticle (NP) of Fe₂O₃@glutamine (C₅H₁₀N₂O₃) was synthesized to improve the Fe₂O₃ properties in absorbing carbon dioxide (CO₂) using the base fluid of hydrous N-methyl-2-pyrrolidone (NMP) solution (50 wt%), as a physically powerful CO₂ absorbent. To do this, several nano-NMP solutions, in different weight percentages of NPs, were first prepared. Then, in a batch setup, the nano-NMP solutions were directly exposed to CO₂ gaseous (at the pressures of 20, 30, and 40 bar) to clarify the effects of the mass percentage of NPs and initial pressure on CO₂ absorption. Results clearly illustrated that Fe₂O₃ nanofluid was not stable more than 0.025 wt%. However, Fe₂O₃@glutamine nanofluid was stable approximately two times more than Fe₂O₃ nanofluid due to the presence of glutamine as a hydrophilic agent in the structure of Fe₂O₃@glutamine. Moreover, in comparison to the base fluid (NMP solution), although Fe₂O₃ increased CO₂ absorption up to 9.14%, Fe₂O₃@glutamine NPs caused the CO₂ absorption to increase up to 19.41%, which can be determined as the chemical reactions of two amino groups in the glutamine structure with CO₂ and also higher stability of Fe₂O₃@glutamine NPs compared to bare Fe₂O₃ NPs. To achieve accurate results, all the mentioned experiments were repeated 5 times. The performance of Fe₂O₃ and Fe₂O₃@glutamine NPs after the fifth trial reduced by less than 3.5%, which reveals that the synthesized NPs had almost stable efficiency throughout their applications.