polyether-block-amide

Hypothesis: PEBA, also known as polyether-block-amide, has emerged as a highly favorable polymer material for the production of CO2 separator membranes. The membranes made from PEBA rely on the solution-diffusion mechanism for separation. However, the trade-off limitation hinders the enhancement of both permeability and selectivity, posing a crucial challenge in the widespread adoption of these membranes in various industries. To address this issue, incorporating compounds that create facilitate transport mechanism into the separation process proves to be a viable solution.

To address the trade-off limitation in polymer membranes, a novel two-way facilitated transfer membrane was developed in this research. This membrane consisted of a PEBA matrix with two different carriers. Aniline was selected for its nucleophilic addition reaction towards CO2, while alumina particles served as carriers for π-complexation reactions. The combination of these two carriers within the polymer matrix resulted in the establishment of a two-way facilitated transport mechanism.

As a result of adding two types of carriers, aniline and alumina, to the PEBA matrix, the permeability of CO2 increased 4.2 times compared to the pure membrane, and the CO2/N2 selectivity also increased 2.1 times compared to the pure membrane, demonstrating the high potential of these two carriers in enhancing separation performance. Molecular simulation results showed that the increase in CO2 permeability was due to the increase in its diffusion coefficient within the membrane thickness, facilitated by the pathways created by alumina and aniline in the polymer matrix. Comparison of the permeability and selectivity of the membrane with other works on the Robeson curve showed that the resulting membrane was able to easily overcome the trade-off limitation, surpass the Robeson boundary, and transform into a membrane suitable for industrial applications in CO2 separation.

In this research, pure polyether block amide (PEBA) membrane and PEBA membrane containing tween surfactant were made using molecular simulation and analyzed from a molecular point of view. In order to investigate the structure of the membranes, their density and free fraction volume were calculated. Also, the radial distribution function was plotted in order to investigate the interaction of CO2 gas with PEBA polymer chains and tween molecules, and the permeability and solubility coefficients against CO2 and N2 gases were obtained. Moreover, the selectivity of CO2 over N2 was calculated for the membranes. The results showed an increase in the solubility and diffusion coefficients of CO2, followed by an increase in the permeability of this gas by adding tween to the polymer matrix, while the selectivity of the membrane containing tween decreased due to the increase in the diffusion coefficient of N2 in this membrane compared to the pure membrane.

Hypothesis: 

One potential method for improving nanocomposite mixed matrix membranes is through the use of nanoparticles and compounds containing hydroxyl and carboxyl groups, which may aid in the penetration of CO2 gas. In this study, we investigated the selectivity and permeability of a polyether block amide/polyvinyl alcohol (Pebax/PVA) nanocomposite membrane containing magnesium oxide (MgO) nanoparticles. Previous research has shown that the addition of MgO to the Pebax/PVA matrix can increase CO2 permeability by creating an intermolecular space.

Prepared a Pebax/PVA nanocomposite membrane with a weight ratio of 80:20, containing 10% MgO nanoparticles, through a solution casting method. Evaluated the performance of the Pebax/PVA/MgO nanocomposite membrane for separating CH4 and CO2 gases using various tests.

Characterized the membranes through Fourier transform infrared (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) tests. FESEM images showed increased surface roughness with the addition of nanoparticles, and the nanoparticles were well dispersed within the polymer matrix. XRD analysis indicated that MgO nanoparticles had more interaction with PVA chains than with Pebax chains, and peaks at 42° and 62° regions were formed due to the placement of MgO nanoparticles among the polymer chains. We studied various parameters, including polyvinyl alcohol and MgO nanoparticle content, pressure, and temperature, as independent variables and examined their effects on the permeability of CH4 and CO2 gases. We measured the permeability of the constructed membranes and found that the addition of MgO significantly increased the permeability of CH4 and CO2.