Solubility and Spectral Investigation of Dilute SO2 in the Binary System Polyethylene Glycol 600 + Water and System's Density, Viscosity, and Surface Tension

Isothermal gas-liquid equilibrium (GLE) data were measured for dilute SO2 in the binary system polyethylene glycol 600 (PEG) + H2O at T = 298.15 K and p = 122.66 kPa, in which SO2 partial pressures were calculated in the range of (0 to 140) Pa. Based on the fitting GLE data, Henry's law constants (Hx) of dilute SO2 in various PEG (1) + H2O (2) mixtures were obtained. Meanwhile, densities, viscosities, and surface tension of the binary system PEG (1) + H2O (2) were also measured over the whole concentration range at T = (298.15 to 323.15) K. From density and viscosity data, the excess molar volumes (VmE) and viscosity deviations (Δη) were calculated. Based on kinematic viscosity data, the enthalpy of activation for viscous flow (ΔH*) and entropy of activation (ΔS*) for the viscous flow were also obtained. Additionally, the important intermolecular interaction among PEG, H2O and SO2 were investigated using UV-Vis, FTIR, and 1H NMR spectroscopic techniques. Spectral results showed that the interaction between PEG and H2O resulted from hydrogen bonding, and the interaction of PEG with SO2 resulted from both the O → S charge-transfer interaction and intermolecular hydrogen bonding.