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 g_SO2/g_DES 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.

中文翻译：

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三元功能性深共晶溶剂对SO _2的高效可逆吸收研究

烟气中低浓度SO ₂的有效和可逆捕获已引起越来越多的关注。在这项工作中，制备了一系列基于1-丁基-3-甲基咪唑鎓盐（BmimCl）作为氢键受体和乙烯脲（EU）以及三唑衍生物作为氢键供体的新型三元功能深共熔溶剂（DES）。研究低浓度SO _2的吸收。结果表明，所研究的三元DES在低浓度下表现出优异的SO ₂捕获性能。值得注意的是，EU / 4-甲基咪唑（4-CH ₃ -Im）/ BmimCl（1：2：1）和EU / 4-CH ₃ -Im / BmimCl（1：1：1）表现出高的SO ₂有效吸收能力。 （0.259和0.209克_{SO 2} / g _DES在0.2 vol％SO ₂和20°C下）和令人满意的解吸效率。此外，三元DES在五周期吸收-解吸实验中显示出高的热稳定性，出色的可重用性和可逆性。此外，光谱研究与量子化学计算相结合，它可以得出结论，4-CH ₃ -Im在DESS化学与SO相互作用₂至有效地捕获SO ₂，和欧盟可以调节活性位点的反应性在4-CH ₃ - Im提高了DES的解吸能力。总体而言，这些三元DES具有出色的脱硫性能（高SO ₂ 有效吸收能力和提高的解吸能力）在烟气脱硫方面具有广阔的前景。