Efficient separation of lithium from alkaline solution with high Na/Li ratio is of great importance for the development of batteries for new energy industry. This work proposes the use of a novel extraction system composed of ethylhexyl salicylate (ES) and trialkylphosphine oxide (TRPO). The equilibrium experiment revealed that the order of metal ions extracted by ES/TRPO extraction system is Mg > Ca > Li > Na > K. A recovery process including extraction, scrubbing, and stripping was designed to recover lithium from a solution of 3.25 g/L Li, 52 g/L Na and 0.8 mol/L OH. More than 99% of lithium could be extracted to the organic phase. After stripping, a lithium-rich solution containing 25 g/L Li was obtained, and the system showed good stability in the cycling experiments. The FT-IR analysis and DFT calculation were conducted to investigate the extraction mechanism. The results demonstrated that ES mainly coordinates with metal ions through Ph-O and CO bonds to form a hexatomic ring complex, thereby allowing metal ions to enter the organic phase. The calculated binding energies of the complex are highly consistent with the equilibrium experiment. The present work may provide a novel extraction system to efficiently recover lithium from alkaline solution with high Na/Li ratio.

中文翻译：

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使用协同萃取剂水杨酸乙基己酯和氧化三烷基膦在煤油中从碱性溶液中高效萃取锂并用酸反萃取


从高Na/Li比的碱性溶液中高效分离锂对于新能源产业电池的发展具有重要意义。这项工作提出使用由水杨酸乙基己酯（ES）和三烷基氧化膦（TRPO）组成的新型萃取系统。平衡实验表明，ES/TRPO萃取系统萃取金属离子的顺序为Mg>Ca>Li>Na>K。设计了萃取、洗涤和反萃的回收工艺，从3.25g/溶液中回收锂。 L Li、52 g/L Na 和 0.8 mol/L OH。 99%以上的锂可以被萃取到有机相中。剥离后得到Li含量为25 g/L的富锂溶液，系统在循环实验中表现出良好的稳定性。通过 FT-IR 分析和 DFT 计算来研究提取机理。结果表明，ES主要通过Ph-O和CO键与金属离子配位，形成六元环络合物，从而使金属离子进入有机相。计算的复合物结合能与平衡实验高度一致。目前的工作可能提供一种新颖的萃取系统，以从高Na/Li比的碱性溶液中有效地回收锂。