Density, viscosity, refractive index and molecular interaction of polyethylene glycol 400 + 1,3-propanediamine deep eutectic solvent for CO2 capture

Abstract

A new deep eutectic solvent (DES) was obtained using polyethylene glycol 400 (PEG400) as the H bond donor (HBD) and 1,3-propanediamine (PDA) as the H bond acceptor (HBA). Meanwhile, density(ρ), viscosity (η) and refractive index (nD) of (PEG400 + PDA) DES at T = (293.15 to 318.15) K with the step size of 5 K were measured under atmospheric pressure. Through the measured base data, excess molar volume (VmE), excess refractive index (nDE), viscosity deviation (Δη), deviation in molar refraction (ΔRM), refractive index deviation(ΔnD), excess Gibbs energy of activation of viscous flow (ΔG∗E), partial molar volume (V1¯ and V2¯), apparent molar volume (Vφ,1 and Vφ,2), molar isobaric thermal expansion (Ep,m) and thermal expansion coefficient (αρ), were systematically calculated and analyzed, and the Redlich-Kister (R-K) equation was used for fitting VmE, nDE, ΔRM, Δη, ΔnD, and ΔG∗E. In addition, several theoretical mixing rules related to refractive index were evaluated and compared with the experimental data. The results showed that there was a specific intermolecular hydrogen bonding interaction in (PEG400 + PDA) DES, which was systemically discussed on the basis of UV–vis, FLS, FTIR and Raman spectral technologies. At the molar fraction with the strongest intermolecular force, the maximum solubility of CO2 per 1 mol PDA was 0.99 mol CO2 at 150 mL/min CO2 flow rate.