Solubility properties and spectral characterization of sulfur dioxide in ethylene glycol derivativesElectronic supplementary information (ESI) available. See DOI: 10.1039/c4ra13874k

Solubilities of SO 2 in ethylene glycol derivatives were determined by dynamic isothermal gas-liquid equilibrium (GLE) experiments, and the thermodynamic parameters of the absorption processes were calculated. The GLE results indicated that the solubilities of SO 2 in ethylene glycol derivatives increase in the order: diols < monomethyl ethers < dimethyl ethers, with the enthalpy values ranging from −23.2 to −43.3 kJ mol −1 . The regeneration experiment found that the absorption of SO 2 in tetraethylene glycol dimethyl ether is reversible, and the solvents can be reused without a significant loss of absorption capacity. The interactions between SO 2 and ethylene glycol derivatives were investigated by UV, IR and NMR. In addition, a 1 H-NMR spectroscopy technique with external references was used to investigate the physical absorption process of SO 2 for the first time, in order to avoid the influence of deuterated solvents. Spectroscopic investigations showed that the interactions between SO 2 and ethylene glycol derivatives are based on both the charge-transfer interaction and hydrogen bond. Ethylene glycol derivatives with desirable absorption capacities and excellent regeneration abilities are promising alternatives to conventional sorbents in SO 2 separation. NMR with external references is applied in the mechanistic study of sulfur dioxide absorption.