Density, Viscosity, and Volumetric Properties of (2-Propoxyethanol + 3-Diethylamino Propylamine) Mixed Solutions at <i>T</i> = 298.15–318.15 K and Atmospheric Pressure for Absorption of CO₂

Density and viscosity properties of 2-propoxyethanol (2-PE) + 3-diethylamino propylamine (DEAPA) mixed solutions were investigated at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K and P = 100.5 kPa. After that, density was fitted well by the least-squares method, and viscosity was fitted well by the Arrhenius equation. According to basic data of density and viscosity, the excess properties and thermodynamic quantities of the mixed solutions were calculated, which indicated that an intermolecular interaction between 2-PE and DEAPA existed. Furthermore, computational chemistry and spectral analyses are used to explore the types of intermolecular interaction forces. Through computational chemistry, the most stable configurations of two organic single molecules and (2-PE + 2-PE, DEAPA + DEAPA, and 2-PE + DEAPA) bimolecules were optimized, and the hydrogen bond (HB) between the molecules was inferred. Through spectral analyses, Raman and 1H NMR spectra were respectively used to characterize the (2-PE + DEAPA) mixed solutions. The hydrogen bonding mechanism was further found to be consistent with computational chemistry. Subsequently, based on the molar ratio of the strong intermolecular interactions, the (2-PE + DEAPA) mixed solutions presented a strong absorption capability of 0.6382 mol of CO2/mol of DEAPA for CO2 fixation at 150 min.