咪唑离子液体及其萃取体系的辐射效应研究

Radiation Effects on Imidazolium Ionic Liquids and Their Extraction Systems

离子液体因其低挥发性、高热稳定性及在萃取金属离子方面的优良表现被认为是乏燃料后处理中萃取分离放射性核素的新一代绿色溶剂。但从乏燃料后处理强辐射的应用环境来看,需要首先对离子液体及其萃取体系的辐射效应进行系统研究和评估。本文以两种常见的憎水性咪唑离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4mim][PF6)]和1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺盐([C4mim][NTf2)]为例,综述了我们在离子液体及其萃取体系的γ辐射效应方面的最新研究进展,内容包括纯离子液体在氮气气氛下的辐射效应,硝酸对离子液体辐射效应的影响,离子液体辐解产物的分离分析及γ辐照对离子液体体系萃取金属离子的影响等。基于以上研究对离子液体用于乏燃料后处理的可行性进行了评估,同时对离子液体及其萃取体系的辐射效应研究进行了展望。

Room-temperature ionic liquids（RTILs）,especially those containing imidazolium cations,for instance 1,3-dialkylimidazolium,associated with various inorganic anions are receiving an ever-increasing amount of interest as environmentally benign alternatives to volatile organic solvents for traditional liquid-liquid extraction of high level radioactive nuclides in nuclear fuel reprocessing,because of their low volatility,good thermal and chemical stability,as well as excellent extraction capacity.The application of RTILs in nuclear fuel reprocessing,however,requires a comprehensive knowledge of radiation effects on RTILs and their extraction systems.Herein,we reviewed our recent investigations of γ-radiation effects on two widely used hydrophobic RTILs [C4mim]X and [C4mim]X-based extraction systems,where [C4mim]＋ is 1-butyl-3-methylimidazolium and X is hexafluorophosphate（PF-6） and bis（trifluoromethylsulfonyl）imide（[NTf2）]-）,respectively.The investigations involved radiation effects on chemical structure and some properties,especially phase behavior and fluorescence properties of neat RTILs under nitrogen atmosphere and of RTILs in the presence of nitric acid,separation and analysis of radiolytic products of RTILs,and influence of γ-irradiation on RTILs-based extraction systems during extraction of metal ions.Based on the results,the feasibility of RTILs as alternative media for the separations of high level radioactive nuclides from spent nuclear fuel was evaluated,and further studies on the radiation effects on RTILs and RTILs-based extraction system are prospected.