Experimental and Speciation Analysis of Biphasic TETA/TMEDA Blend for CO₂ Capture

Abstract Biphasic solvents show promise for CO 2 capture due to lower energy consumption but face challenges like high regeneration energy and phase separation instability. This study introduces a biphasic aqueous solvent system with triethylenetetramine (TETA) and tetramethylethylenediamine (TMEDA). The effects of TETA:TMEDA ratios on CO 2 absorption, viscosity, density, and phase separation were tested at various temperatures and compared to 5 M mono‐ethanolamine (MEA). The optimal 1.5 M TETA:2.5 M TMEDA at 40 °C captured 0.72 mol CO 2 mol −1 amine, with 84 % CO 2 in the lower phase. Desorption at 90 °C achieved 0.43 mol CO 2 L −1 , improving cyclic capacity by 62 % over MEA. The solvent required 2.77 GJ t CO 2 −1 for regeneration, 22 % less than MEA. Nuclear magnetic resonance (NMR) analyses elucidated reaction mechanisms and phase behavior. Stability was confirmed by over 10 absorption–desorption cycles.