Sustainable Surface Active Amine Regeneration for Carbon Recovery as Bicarbonate via Energy-Efficient Electrodialysis

Abstract

Thermal regeneration of amine solvents for carbon capture is energy intensive, typically requiring 3–4 MJ/kg CO2. Recovering CO2 directly as bicarbonate offers a more economical and thermodynamically favorable alternative when coupled with electrochemical separation. Here, we show that a conventional electrodialysis (ED) process can simultaneously regenerate a tertiary surface active amine (N-10PO) while recovering captured carbon as sodium bicarbonate under ambient conditions. The ED system employed a tailored anion–anion–cation (AAC) membrane configuration that retained the amine while selectively transporting bicarbonate. Specific energy consumption (SEC) was minimized at 1 mA/cm2 to be 1.5 MJ/kg CO2, as compared to 3–4 MJ/kg CO2 for thermal regeneration. The performance of both amine regeneration and carbon recovery was consistent across three testing cycles, and sodium hydroxide addition needed for regeneration did not lead to degradation of membrane performance reused for over a year. Experiments at increasing current densities from 1–8 mA/cm2 led to increased regeneration rates 0.138 (±0.008, n = 3) to 0.637 (±0.037, n = 3) mol C recovered/min at the expense of increased SEC from 1.56 (±0.16, n = 3) to 6.0 (±0.93, n = 3) MJ/kg CO2. Overall, the proposed process provides system simplicity, modularity, and compatibility with renewable energy integration.