Process Parametric Investigation of Graphene-Oxide-Embedded Composite Membranes for Boosting CO₂/N₂ Separation

Abstract

Membrane technology for carbon capture has been favored to mitigate climate change attributed to the greenhouse effect in recent years. The implementation of composite membranes with a selective layer made from CO 2 -selective polymers and nanofillers is gaining particular interest for efficient CO 2 capture, with the benefits of easy processability, costeffectiveness, and excellent separation performance. Graphene oxide (GO) with abundant oxygen-containing functional groups exhibits tremendous potential for enhancing mechanical and transport properties when incorporated into the polymeric matrix. Herein, a GO-reinforced polyacrylamide/poly(vinyl alcohol)/polysulfone (PAM/PVA/PSf) composite membrane was developed with a focus on improving the CO 2 /N 2 separation performance. The membrane performance was tested with mixed gas (10/90 vol % CO 2 /N 2 ) under humidified conditions. The effects of the preparation parameters (e.g., GO content and pH of the casting solution) and the operating parameters (e.g., feed flow rate, feed pressure, temperature, and relative humidity) were systematically investigated and further optimized to identify the optimal condition for post-combustion carbon capture. The best membrane performance with a CO 2 /N 2 selectivity of 65 and a CO 2 permeance of 55 gas permeance units (GPU) at 2 bar and 30 °C was documented in this study. The development of CO 2 -selective composite membranes may address the challenges associated with the upscaling of membrane technology for potential industrial carbon capture.

Molecular Engineering of Copoly(ionic liquids)-Based Membranes for CO2 Separation

“…Moreover, the CO 2 /N 2 selectivity also decreases from 66 to 40, which is consistent with the tendency reported in the literature. 34,49 Carrier saturation and the reduced absolute water content and membrane compaction at higher pressures can cause less contribution from CO 2facilitated transport and reduce gas diffusivity, which leads to the decrease of CO 2 permeance. 34 While the influence of pressure on N 2 permeance is not so significant, and eventually results in the decrease of the CO 2 /N 2 selectivity as well.…”

“…34,49 Carrier saturation and the reduced absolute water content and membrane compaction at higher pressures can cause less contribution from CO 2facilitated transport and reduce gas diffusivity, which leads to the decrease of CO 2 permeance. 34 While the influence of pressure on N 2 permeance is not so significant, and eventually results in the decrease of the CO 2 /N 2 selectivity as well. Therefore, the lower operating pressure is favorable for the application of the developed membranes in the CO 2 /N 2 separation.…”

“…Inspired by those studies, copolymerizing the functionalized polymers with IL monomers can potentially provide an efficient solution to enhance the CO 2 separation performances. Considering the functionalized polymers, PAM with high CO 2 adsorption capacity and hydrophilicity raised the perspective of being membranes for CO 2 separations. , Alternatively, the monomer of butyl acrylate (BA) was also reported to be incorporated into PILs to fabricate soft and flexible membranes . It is expected that BA possessing a higher fractional free volume can promote gas penetration through a membrane to enhance gas separation efficiency.…”