Solubility of dilute SO2 in binary system of polyethylene glycol 200 and dimethyl sulfoxide as a function of liquid composition and system's spectroscopic studies

In a previous work, the binary mixture of polyethylene glycol 200 (PEG) and dimethyl sulfoxide (DMSO) was used as a promising medium for absorption of SO 2 ( J. Chem. Eng. Data 2015 , 60 , 2135). As a continuation of the previous study, the solubility data of dilute SO 2 in the binary mixture of PEG   +   DMSO were measured by isothermal gas-liquid equilibrium experiments at 298.15   K and 122.66   kPa with SO 2 partial pressure below 128   Pa in the gas phase. The solubility of SO 2 decreased gradually with increasing mass fraction of PEG in the mixtures. We found that the absorption process, which obeyed Henry's law within the given experimental conditions, was physical absorption , and Henry's constants were further calculated from solubility data. Furthermore, to obtain important information about the absorption mechanism, the inter-molecular interactions among SO 2 , PEG, and DMSO were investigated by UV, FTIR, and 1 H NMR spectroscopic techniques. Spectral results showed that the interactions among SO 2 , PEG, and DMSO were resulted from both intermolecular hydrogen bonding and the O   →   S charge-transfer interaction.