Deep eutectic solvents (DESs) have been seen as promising absorbents for SO₂ capture in recent years. In this work, a series of DESs based on imidazole derivatives were synthesized to investigate the low pressure SO₂ absorption. The physical properties were determined, and the DESs exhibited low viscosities and high stability. Effects of composition, operating temperature and pressure, and water content on SO₂ absorption capacity were investigated. It was demonstrated that the 1-butyl-3-methylimidazolium chloride (BmimCl):4-methylimidazole (4CH₃-Im) (1:2) could absorb 1.42 and 0.189 g_SO2/g_DES at 101.3 and 1 kPa SO₂ partial pressure, respectively, which were higher than most reports to date under this condition. The absorbed SO₂ could be released easily under mild condition, and there was no change in absorption performance after 5 cycles. Furthermore, the absorption mechanism studied by FTIR and NMR indicated that the high SO₂ absorption capacity originated from the synergistic interaction of BmimCl and 4CH₃-Im on SO₂. This work opens opportunity for low partial pressure SO₂ capture and insight into the formation mechanism of DESs for further investigation.

中文翻译：

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功能性深共晶溶剂对低压分压SO ₂的高效可逆捕集

近年来，深共晶溶剂（DES）被认为是有前途的吸收SO _2的吸收剂。在这项工作中，合成了一系列基于咪唑衍生物的DES，以研究低压SO _2的吸收。测定了物理性质，并且DES显示出低粘度和高稳定性。研究了组成，操作温度和压力以及水含量对SO ₂吸收能力的影响。结果表明，1-丁基-3-甲基咪唑氯化物（BmimCl）：4-甲基咪唑（4CH ₃ -Im）（1：2）在101.3和1 kPa SO ₂下可以吸收1.42和0.189 g _{SO 2} / g _DES。分压，这比迄今为止在这种情况下的大多数报告都高。被吸收的SO ₂在温和的条件下容易释放，并且在5个循环后吸收性能没有变化。此外，通过FTIR和NMR研究的吸收机理表明，高SO ₂吸收能力源自BmimCl和4CH ₃ -Im在SO ₂上的协同相互作用。这项工作为低分压的SO ₂捕集和深入了解DES的形成机理提供了机会，以供进一步研究。