Absorption, Desorption, and Mechanism Investigation of Dilute SO2 in the 1,3-Propanediol + Dimethyl Sulfoxide Binary System

In this work, the absorption of sulfur dioxide (SO₂) was investigated using the 1,3-propanediol (PDO) + dimethyl sulfoxide (DMSO) system, and the gas−liquid equilibrium (GLE) data were analyzed over a temperature range of 298.15–318.15 K (with a temperature gradient of 5 K) at a pressure of 123.15 kPa. By fitting the gas–liquid equilibrium data, it is observed that the process of absorption SO₂ conforms to Henry’s Law. The change in specific entropy, enthalpy, and Gibbs free energies of the SO₂ absorption process was as well calculated. In addition, the capture and regeneration properties of the PDO + DMSO system were investigated under atmospheric pressure, and the results of regeneration experiments demonstrated that 97.3% of SO₂ could be desorbed by heating and bubbling with N₂. Furthermore, there was no notable reduction in absorption capacity of the absorbent solvents after multiple cycles. Finally, the FTIR spectra and computational information were noted to analyze the interaction between SO₂ and the system. As a result, an intermolecular hydrogen bonding association between PDO, DMSO, and SO₂ can be inferred.