Physicochemical Properties, Interaction Analysis, and CO2 Capture Capacity for the Binary Mixtures of Ethylene Glycol and 1,3-Propanediamine

In this study, the density (ρ) and viscosity (η) of the mixed solvent of ethylene glycol (EG) and 1,3-propanediamine (1,3-PDA) were experimentally measured over a temperature range of 293.15–318.15 K under an experimental pressure of 100.5 kPa. From these measurements, the excess molar volumes (V_m^E), partial molar volume (V̅), excess activation Gibbs energy (ΔG^*E), and coefficient of thermal expansion (α_p) of the binary mixtures were derived. The Redlich–Kister (R-K) equation was employed to fit the data for excess molar volume (V_m^E), viscosity deviation (Δη), and excess activation Gibbs energy (ΔG^*E). Strong hydrogen bonding interactions between EG and 1,3-PDA were confirmed through spectroscopic analyses and density functional theory (DFT) calculations. Furthermore, the binary mixture exhibiting the strongest intermolecular interactions demonstrated an exceptional CO₂ uptake capacity of up to 0.98 mol of CO₂/mol of PDA, significantly higher than the 0.49 mol of CO₂/mol of PDA observed for pure 1,3-PDA. This enhancement in CO₂ absorption can be attributed to the strong hydrogen bonding interactions that suppress the volatility of 1,3-PDA.