磷酸酯功能化离子液体萃取剂的相变萃取提锂机理研究

Study on Phase Change Extraction Lithium Mechanism of Phosphate Ester Functionalized Ionic Liquid Extractant

萃取法提锂是卤水提锂领域应用广泛的分离方法,然而存在环境污染大,易产生第三相等问题。离子液体不仅可以降低传统溶剂萃取因有机溶剂挥发造成的环境污染,而且能够有效避免提锂过程中第三相的产生。本工作制备了四种磷酸二丁酯离子液体,并将其用于萃取锂的研究。所制备的离子液体含有对Li+有络合能力的磷酸酯,而且这类离子液体具有酸碱调控亲疏水的特性;离子液体在萃取段能够与水互溶,使离子液体与Li+充分络合;在分相段通过加入酸使离子液体发生相转移,实现萃取相与卤水分离。萃取过程不需要协萃剂的使用且没有第三相的产生。在最优条件下,离子液体[Bmim][DBP]的单级锂萃取率可达70.12%。通过光电子能谱等表征手段研究了萃锂机理。

Extraction is a widely used separation method in the field of extracting lithium from brine.However,the environmental pollution problem and the third phase generation problem always exist in the extraction process.Ionic liquid can not only reduce the environmental pollution caused by the volatilization of organic solvent,but also can avoid the generation of the third phase in traditional lithium extraction process.In this work,we prepared four dibutyl phosphate functionalized ionic liquids and used them for lithium extraction.The prepared ionic liquid contains phosphate groups that can coordinate with Li+,whose hydrophilic and hydrophobic properties can be regulated by acid-base property.The ionic liquid can be miscible with water in the extraction stage,so that the ionic liquid and Li+are fully complexed.In the phase separation section,the ion liquid loaded with lithium phase transfer to realize the separation of extraction phase and brine after adding the acid solution with low concentration.The extraction process does not require the use of synergistic agent.Besides,there is no the third phase is generated.Under the optimal conditions,the single stage lithium extraction rate of[Bmim][DBP]ionic liquid can reach 70.12%.The lithium extraction mechanism of ionic liquid was studied by means of photoelectron spectroscopy.