Fundamental properties and intermolecular interaction of triethylene glycol plus ethylenediamine aqueous solution for CO2 capture

Solvent absorption as a significant method for carbon dioxide capture, exploring the mechanism of CO 2 capture and regeneration solvents is essential for industrial applications. In this work, water (H 2 O) + (ethylenediamine (EDA) + triethylene glycol (TEG)) system with the constant mole ratio (TEG: EDA = 1: 1) was chosen as the liquid absorbent. In order to gain a deeper comprehension of solution properties of H 2 O + (EDA + TEG) system, the density ( p ) and viscosity ( I ) of fundamental properties were measured at P = 1005 hPa and T = (298.15 K to 318.15 K) with the temperature step of 5 K. The excess properties, including excess molar volume (V E m ), viscosity deviation ( d I ), and excess Gibbs energy of activation of viscous flow ( Delta G & lowast; E ) of H 2 O + (EDA + TEG) system were calculated from the experimental p and I values, and fitted well with the Redlich-Kister polynomial equation. The above results combined with the spectra proved the existence of intermolecular interaction in H 2 O + (EDA + TEG) system, which favorably fixed CO 2 . Subsequently, the aqueous solution with mass fraction of 15 wt % EDA and molar ratio EDA: TEG = 1: 1 was used for absorbing CO 2 (room temperature) and desorbing (378.15 K) for 5 -time cycles, and the cycling absorption performance decreased. So as to explore the reason of degradation, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance carbon spectroscopy ( 13 C NMR) were used to analyze the circulating absorption mechanism of CO 2 in H 2 O + (EDA + TEG) system, which revealed that alkyl carbonates and partially indecomposable substance 2-imidazolidinones generated in the cyclic process, and provided some implications for the industrial application.