Performance of a novel CO2 absorption and reverse electrodialysis system with different amine solutions for simultaneous energy and bicarbonate recovery

Abstract

In this study, the performance of a novel integrated carbon dioxide (CO2) capture and reverse electrodialysis (RED) system was evaluated. The optimal operating conditions and carbon dioxide absorption and desorption mechanisms were identified. The proposed system utilizes a RED device to recover energy from the desorption step of the CO2 capture process, which is known to have high energy requirements in conventional processes. It has the potential as a hybrid process capable of recovering absorbent, energy, and bicarbonate through RED. To verify the performance of the system, CO2 loading, power density, and absorbent regeneration were evaluated using primary (monoethanolamine, MEA), secondary (diethanolamine, DEA), and tertiary (N-methyldiethanolamine, MDEA) amines. In the case of primary and secondary amines, carbamates, intermediate products, are formed and pass through the ion exchange membrane of RED, thereby achieving high power density. However, they are re-substituted with amines after passing through the ion exchange membrane (IEM), leading to the loss of absorbent. Conversely, in the case of tertiary amines, no intermediate products were formed, and excellent absorbent regeneration performance of more than 99.9% was demonstrated through multi-stage RED. Through this, the feasibility of future applications of this technology was confirmed.