离子液体-冠醚体系萃取分离锂同位素及机理的研究

Lithium consists of 6Li and 7Li two stable isotopes in nature, 6Li( 7.5 at%) and 7Li(92.5 at%) in relative abundance. 6Li was used as nuclear raw materials for hydrogen bomb to rapidly produce tritium , protective materials of neutron for fission reactor to absorb neutron, and fuel for fusion power reactor to produce tritium. 7Li is the most ideal heat transfer medium of fusion power reactor and neutral medium of thorium-based fused salt reactor. Thus, lithium isotopes will play an increasingly important role in nuclear power industry in the future. There is a great need to develop green and efficient method for lithium isotope separation..Ionic liquids (ILs) are being considered as replacement solvents for synthetic, catalytic, electrochemical, and separations processes as a result of their unique chemical and physical properties. Ionic liquid have no detectable vapor pressure and are relatively thermal stable. So there is no loss of solvent through evaporation with Ionic Liquids. This will avoid environmental and safety problems due to volatilization, as is the case in traditional organic solvents. Therefore, they are proposed as novel solvent systems to replace traditional solvents that are generally toxic, flammable, and volatile. Ionic Liquids are regarded to have the potential to be alternative reaction media for “Green Chemistry”..In this work, a new liquid/liquid extraction system, ionic liquid (alkyl imidazole)-crown ether (different branches ) was used for the separation of the lithium isotope. Depending on quantum chemistry calculation and spectrum technology, the interaction among ionic liquids, crown ether and isotopes for the separation of Lithium isotopes will be studied. This ionic liquids-crown ether solution structure and their coordination behavior with lithium isotopes will be analyzed by DFT (Density Functional Theory).And the mechanism of extraction will be investigated in this system. This separation system is green and efficiently. In this study, we try to improve the separation efficiency of this system. Through this study, theoretical support for the extraction of lithium isotopes from salt lakes will be provided.

锂元素是重要的战略元素，锂同位素是核工业发展的重要原材料。对高纯度锂同位素的需求日益增加，锂同位素分离研究意义重大。对盐湖卤水中的锂同位素资源加以分离和开发，将有助于提高我国的能源安全，推动生态环境的改善。.本项目采用烷基咪唑类离子液体-不同支链冠醚体系萃取分离锂同位素，以高效环保的方式进行锂同位素的分离，提高锂同位素的分离效率，研究离子液体、冠醚对锂同位素分离的影响。并通过密度泛函理论计算并结合光谱分析，开展该体系溶液结构的解析，及与锂同位素的配合行为研究，探索适用于离子液体-冠醚体系的萃取分离锂同位素机理，为利用离子液体-冠醚体系分离提取盐湖卤水中的锂同位素提供基础理论数据。

锂(Li)是最轻的金属，锂的最大用途在于其可以提供新的能源。元素锂在自然界有6Li 和7Li 两种稳定同位素，其丰度分别约为7.5%和92.5%， 6Li 是必不可少的核聚变堆燃料。7Li 被用来作为核聚变反应堆的堆心冷却剂和导热的载热剂。将6Li 和7Li 分离的过程称为锂的同位素分离。由于6 Li 在核发电和氢弹生产中具有非常重要的作用，因此锂的同位素分离研究意义重大。本项目主要采用烷基咪唑类离子液体-不同支链的冠醚体系萃取法分离锂同位素，并探索不同烷基的咪唑类离子液体及不同支链冠醚对锂同位素分配系数的影响。采用拉曼光谱（Raman）、红外光谱（IR）等技术，探索烷基咪唑类离子液体-不同支链的冠醚体系进行锂同位素分离过程中该体系中的溶液结构信息及锂同位素的配位结构。 将光谱学手段与密度泛函理论 (DFT) 计算相结合，研究离子液体、冠醚和锂同位素之间的相互作用及对锂同位素配位方式的影响。通过对不同支链的冠醚与离子液体体系的分析，不同支链的冠醚对各种锂盐都具有一定的同位素分离效应，其锂同位素分离系数可高达1.04。B15C5-离子液体经10级逆流萃取。测得6Li/7Li的分离系数为1.0318，6Li丰度也由初始水相中的7.548%富集到7.7184%。.本实验还发现10-羟基苯并喹啉萃取体系在一定的实验条件下具有可观的单级萃取率，同时，其单级的分离效应在1.019左右，该体系具有一定的分离锂同位素价值。本项目利用离子液体-不同支链冠醚体系萃取法分离提取锂同位素，将离子液体应用于锂同位素的分离，过程高效环保。整个过程包括材料学、化学分析、仪器分析以及化学反应过程研究，对于锂同位素的分离具有广泛的应用前景。