Practical and accessible applications of CO2-captured absorbents through electrostatic ion exchange.

To address intensified global warming, it is urgently necessary to suppress CO2 emissions, particularly from fossil fuel industries. This does not imply reducing manufacturing activities, but rather preventing the release of CO2 generated during industrial processes into the atmosphere by utilizing the waste CO2 within a closed CO2 cycle. Numerous methods based on chemical conversion and biological fixation have been developed; however, these technologies have not yet provided effective solutions to the rising atmospheric CO2 concentration and ocean acidification because of limitations in scalability and practical implementation. Unlike these CO2 conversion approaches, physical CO2 capture through absorption and adsorption does not directly reduce the global carbon budget. Nevertheless, these approaches could help suppress CO2 emissions from industrial processes by utilizing CO2-captured absorbents as functional materials for innovative and improved technologies. This feature article reviews practical and readily accessible methodologies and applications of commercially available amine-based absorbents that capture CO2 as carbonic acid (CA), with particular emphasis on their use as (bi)carbonate-based electrolytes, scavengers of water-soluble pollutants from wastewater, and polymer surfactants for the fabrication of nanoarchitectures. Particular attention is given to the electrostatic interactions between positively charged amines and external anionic compounds through ion exchange. The article also highlights state-of-the-art technologies based on this methodology-CA capture, ion exchange, and regeneration-and discusses future perspectives on the importance of capturing CO2 as carbonic acid.