Liu Shang-Hao, Chen Chan-Cheng, Zhang Bin, Wu Jian-He
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology (AUST) Huainan Anhui 232001 China
Department of Safety, Health and Environmental Engineering, National Kaohsiung University of Science and Technology No. 1, University Rd., Yanchao Dist. Kaohsiung City Taiwan Republic of China
RSC Adv. 2020 Jun 11;10(38):22468-22479. doi: 10.1039/d0ra01821j. eCollection 2020 Jun 10.
Ionic liquids (ILs) have very low volatility and are consequently considered as a green replacement to the organic solvents that have been widely used to date. The fire and explosion hazards of traditional organic solvents primarily depend on the combustibility of their vapors; therefore, ILs have been regarded as nonflammable for a long time because of their low volatility. However, recent studies have shown that ILs are flammable due to their thermal stability and consequently, the fire and explosion hazards of ILs limit their practical applications. The compound 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (abbreviated as [EMIM][TfN]) has been considered a potential candidate solvent for surfactant systems, but studies about the fire and explosion hazards of this IL are rare in the literature. In this study, the fire and explosion hazards of [EMIM][TfN] were explored in terms of different aspects. The auto-ignition temperature of [EMIM][TfN] was found to be 478 °C with an ignition delay time of 12.6 s. It was observed with the TGA/DSC system that the decomposition of [EMIM][TfN] was endothermic in a nitrogen atmosphere but exothermic in an air atmosphere. The dynamic TGA curves showed that the apparent activation energies were the same in both nitrogen and air atmospheres, but the dynamic DSC curves showed that the apparent activation energies were different in nitrogen and air atmospheres. The apparent activation energy inferred from the DSC curve in an air atmosphere was found to be the same as the apparent activation energy estimated by the Semenov theory of thermal ignition. Analysis of the gaseous decomposition products of [EMIM][TfN] by the TGA-FTIR system indicated that the exothermal effect in the air atmosphere was caused by the auto-ignition of acetylene (which is one of the gaseous decomposition products) and not by decomposition itself.
离子液体（ILs）具有极低的挥发性，因此被视为一种绿色替代品，可替代迄今为止广泛使用的有机溶剂。传统有机溶剂的火灾和爆炸危险主要取决于其蒸气的可燃性；因此，由于离子液体挥发性低，长期以来一直被视为不可燃。然而，最近的研究表明，由于其热稳定性，离子液体是可燃的，因此，离子液体的火灾和爆炸危险限制了它们的实际应用。化合物1-乙基-3-甲基咪唑双（三氟甲基磺酰）亚胺（简称为[EMIM][TfN]）被认为是表面活性剂体系的潜在候选溶剂，但关于这种离子液体火灾和爆炸危险的研究在文献中很少见。在本研究中，从不同方面探讨了[EMIM][TfN]的火灾和爆炸危险。发现[EMIM][TfN]的自燃温度为478℃，着火延迟时间为12.6秒。用TGA/DSC系统观察到，[EMIM][TfN]在氮气气氛中的分解是吸热的，但在空气气氛中是放热的。动态TGA曲线表明，在氮气和空气气氛中表观活化能相同，但动态DSC曲线表明，在氮气和空气气氛中表观活化能不同。在空气气氛中从DSC曲线推断出的表观活化能与热着火的谢苗诺夫理论估计的表观活化能相同。通过TGA-FTIR系统对[EMIM][TfN]的气态分解产物进行分析表明，空气气氛中的放热效应是由乙炔（气态分解产物之一）的自燃引起的，而不是由分解本身引起的。
