Binary System of Polyethylene Glycol 200 (1) + 3-Dimethylamino-1-propylamine (2) for CO2 Absorption: Thermophysical Properties and Spectroscopic Study

As the concentration of CO2 in the atmosphere keeps increasing, the development of a highly efficient CO2 absorbent is highly desired. In this work, a binary mixture system of polyethylene glycol 200 (PEG 200) (1) + 3-dimethylamino-propylamine (DMAPA) (2) was used for CO2 absorption. Considering the importance of thermophysical properties to binary solutions, the densities and viscosities of the PEG 200 (1) + DMAPA (2) mixture were measured at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K and atmospheric pressure over the entire composition range. Based on the density and viscosity data, the excess properties and viscous flow thermodynamic parameters were calculated, respectively. To obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities, the excess molar volume (V m E), the viscosity deviation (Δη), and the excess Gibbs free energies of activation for viscous flow (ΔG* E) were fitted to the Redlich-Kister equation. Furthermore, based on the results of UV-vis, FTIR, and 1H NMR spectra, the intermolecular interaction of PEG 200 and DMAPA was discussed. Particularly, a strong intermolecular bonding is formed when the molar ratio of PEG 200 to DMAPA is about 1:2 because of the excess molar volume (V m E). On that account, a mixture of PEG 200 and DMAPA in a ratio of 1:2 was used for studying CO2 absorption, and a CO2 absorption of about 0.19 g per gram of absorbent was achieved at room temperature and atmosphere.