Efficient Absorption of SO₂ by EmimCl-EG Deep Eutectic Solvents

Abstract

In this work, we investigated SO2 absorption by deep eutectic solvents (DESs) formed by 1-ethyl-3-methylimidazolium chloride (EmimCl) and ethylene glycol (EG) under different conditions. DESs with different molar ratios of EmimCl and EG (from 2:1 to 1:2) were prepared. The results showed that all the EmimCl-EG solvents were very efficient for SO2 capture. It was demonstrated that the SO2 solubility increased with increasing concentrations of EmimCl in DESs. The effects of temperature and SO2 partial pressure were also investigated. The Emim-EG (2:1) solvent could absorb 1.15 (53 wt %) g SO2/g solvent at 20 °C and 1.0 atm, a much higher capacity than that of other DESs reported to date under the same conditions. Moreover, the SO2 desorption temperature of the solvents could be tuned by changing the composition of the solvents, and all the EmimCl-EG solvents showed excellent reversibility. Nuclear magnetic resonance and Fourier transform infrared spectra showed the interactions of the solvents and SO2.