Absorption and spectroscopic investigation of sulfur dioxide in tetraethylene glycol aqueous solution

Ether-rich tetraethylene glycol is an alternative SO 2 absorbent due to the good solubility and high stability. Due to the high viscosity of tetraethylene glycol, it is usually necessary to add an appropriate amount of water to reduce the viscosity. In this case, insight into the interaction mechanism between molecules can guide the most reasonable amount of water to be added to tetraethylene glycol in the actual SO 2 gas separation process. In this work, the structure–activity relationship of SO 2 in tetraethylene glycol and its aqueous solution was studied by measuring the SO 2 solubility and spectral features. Using an isochoric saturation method, the solubility of SO 2 in tetraethylene glycol (1) + water (2) mixtures was determined at 303.2 K and pressures up to 120 kPa. It was found that the solubility of SO 2 increases gradually with increasing mass fraction of tetraethylene glycol and the dissolution process of SO 2 conforms to Henry’s law within the current experimental conditions. The Henry’s constants were further calculated based on solubility data. Furthermore, FTIR, UV–Vis, and 1 H NMR spectroscopic characteristic for dissolved SO 2 into tetraethylene glycol (1) + water (2) mixture was also investigated, revealing significant information about the SO 2 absorption mechanism.