Experimental Solubility and Absorption Mechanism of Dilute SO₂ in the Binary System of Diethylene Glycol Monomethyl Ether and Dimethyl Sulfoxide

Abstract

In this paper, a diethylene glycol monomethyl ether (DGME) + dimethyl sulfoxide (DMSO) system was used for the absorption of dilute SO2, and the gas–liquid equilibrium (GLE) data of the binary system for SO2 at p = 123.15 kPa and T= (303.15 K-318.15 K) were measured by a GLE device. Meanwhile, different temperatures and different ratios were also measured, Henry’s constants at different temperatures were fitted based on the measured data, and the thermodynamic parameters of dissolution enthalpy, dissolution entropy, and dissolution Gibbs free energy of the dissolution process were calculated. The results of five cycles of SO2 absorption and resolution showed that the maximum absorption of SO2 in the binary system was 0.85 g/g. The desorption rate could reach 97%, and the absorption and desorption capacities did not decrease significantly after the cycle. The mechanism of SO2 absorption in the binary system was discussed and analyzed by combining spectral analysis and quantum chemistry. The spectroscopic results show that the weak interaction forces between DGME, DMSO, and SO2 are hydrogen bonding forces and dipole–dipole interaction forces, which lay the theoretical foundation for the application and practice of binary hybrid systems. This can provide important GLE data for the design and operation of organic solvent absorption and desorption of SO2 in flue gas desulfurization, and the prepared absorbent has a potential industrial application value.