Investigation of Highly Efficient and Reversible Absorption of SO2 Using Ternary Functional Deep Eutectic Solvents

Hou, Shuai Zhang, Congcong Jiang, Bin Zhang, Haiming Zhang, Luhong Yang, Na Zhang, Na Xiao, Xiaoming Tantai, Xiaowei*

Cite this: ACS Sustainable Chem. Eng. 2020, 8, 43, 16241–16251

Publication Date:October 22, 2020.


The efficient and reversible capture of low-concentration SO2 in flue gas has attracted increasing attention. In this work, a series of novel ternary functional deep eutectic solvents (DESs) based on 1-butyl-3-methylimidazolium chloride (BmimCl) as a hydrogen bond acceptor and ethylene urea (EU) along with azole derivatives as hydrogen bond donors were prepared to investigate the low-concentration SO2 absorption. Results demonstrated that the studied ternary DESs exhibited superior SO2 capture performance at low concentration. Of note, EU/4-methylimidazole (4-CH3-Im)/BmimCl (1:2:1) and EU/4-CH3-Im/BmimCl (1:1:1) exhibited high SO2 available absorption capacity (0.259 and 0.209 gSO2/gDES at 0.2 vol % SO2 and 20 °C) and satisfactory desorption efficiency. Furthermore, the ternary DESs showed high thermostability, outstanding reusability, and reversibility during the five-cycle absorption–desorption experiments. Moreover, combining spectroscopic investigations with quantum chemical calculations, it can be concluded that 4-CH3-Im in DESs chemically interacted with SO2 to effectively capture SO2, and EU could tune the reactivity of the active site in 4-CH3-Im to improve the desorption capability of DESs. Overall, these ternary DESs with distinguished desulfurization performance (high SO2 available absorption capacity and improved desorption capability) have promising prospects in flue gas desulfurization.

Graphical abstract


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