Efficient and remarkable SO2 capture: A discovery of imidazole-based ternary deep eutectic solvents

Abstract

Developing an adsorbent with optimal absorption capacity for SO2 elimination has been an important issue, yet a great challenge remains. Herein, we initiated a series of ternary deep eutectic solvents (DESs), consisting of diethylenetriamine (DETA), ethylene glycol (EG) and 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) with various molar ratio for the systematical investigation of SO2 absorption. It was found that DES with the molar ratio of 2: 1: 2 (DETA: EG: [Emim]Cl) exhibits remarkable absorption capacity (1.02 g SO2/g DES) and robust reusability for SO2 at room temperature and ambient pressure, which is distinctively higher than most of the reported binary DESs so far. Moreover, FT-IR, 1H NMR, 13C NMR together with DFT calculations were adopted to clarify the absorption mechanism for SO2. It indicates that the remarkable absorption capacity might be ascribed to the existence of multiple absorption sites. Therefore, this study offers a promising alternative for the design and preparation of highly effective absorbents for gas elimination.