Excess Properties, FT-IR Spectral Analysis, and CO2 Absorption Performance of Monoethanolamine with Diethylene Glycol Monoethyl Ether or Methyldiethanolamine Binary Solutions

In this study, densities and viscosities of the binary solutions of monoethanolamine with diethylene glycol monoethyl ether or methyldiethanolamine were determined at 293.15, 298.15, and 303.15 K and <i>p</i> = 100.5 kPa. The experimental density data were tested with different equations as a function of composition (Belda and Herraez equations) and as a function of temperature and composition (Emmerling et al. and Gonzalez-Olmos-Iglesias equations). The results show that the Herraez and Emmerling et al. equations best correlate the experimental data. The experimental values of viscosity were tested with different models based on one, two, three, or four parameters. The values of excess molar volume (<i>V</i>^E), viscosity deviation (Δ<i>η</i>), and excess Gibbs energy (Δ<i>G</i>*^E) were calculated from the experimental values and were fitted to the polynomial equations. The values of the excess molar volume are negative for both systems, while positive values were obtained for the viscosity deviation and excess Gibbs activation energy. The values of thermodynamic functions of activation of viscous flow were determined and discussed. The Fourier transform infrared spectroscopy (FT-IR) spectra of the binary solutions analyzed in this study enabled the understanding of the interactions among the molecules in these solutions. In addition, the CO₂ absorption capacity of the binary solutions of monoethanolamine with diethylene glycol monoethyl ether or methyldiethanolamine was determined experimentally.