(166a) Electrochemical Marine Carbon Dioxide Removal from Oceanwater
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Electrochemical Separations Toward Sustainability: Analytical Techniques and Emerging Applications (Invited Talks)
Wednesday, November 8, 2023 - 12:35pm to 1:30pm
Current approaches for the removal of CO2 from oceanwaters rely on water splitting via, bipolar membrane catalysis and electrodialysis for pH modulation to release the CO2 as a gas (low pH) or carbonate salt (high pH). We have proposed an alternative approach to marine carbon dioxide removal (mCDR) that does not require expensive membranes or addition of chemicals, is easy to deploy, and does not lead to formation of byproducts or secondary streams. In this approach, the pH is regulated through a chloride-mediated reaction with electrodes in asymmetric electrochemical cells through which the seawater flows. In the acidification cell the DIC speciation shifts from bicarbonate and carbonate to CO2 which can then be removed in a membrane contactor. The now-decarbonized water is introduced to a second electrochemical cell where the reverse reaction is promoted, the electrodes are regenerated, and the pH increases before the water is discharged back to the ocean. The CO2 removal approach has perceived advantages in that it does not require expensive membranes or addition of chemicals, is easy to deploy, and does not lead to formation of byproducts or secondary streams.
We will discuss the overall electrochemical swing process, which can be enhanced through flexible electrode configurations to reduce transport and electrical resistances while enabling treatment of large quantities of water. Novel methods for the recovery of molecular CO2 without the need for high vacuum desorption, and of calcium carbonate precipitates without fouling of the electrodes, will be highlighted.