In this paper, we proposed a microextraction approach for the extraction and separation of Mn(II) and Co(II) from sulfate solution simulating leachate of spent lithium-ion battery cathode materials using saponified di-(2-ethylhexyl)phosphoric acid system. The effects of the following operational variables were investigated: equilibrium pH, tri-n-butyl phosphate concentration, saponification rate, two-phase ratio and residence time. The results showcased that the microextractor can reach the extraction equilibrium within 20 s, thereby greatly reducing necessary extraction time comparing to that of conventional processes. The volumetric mass transfer coefficient showed 8–21 times larger than that of batch device. With the help of microextractor, 95% of Mn(II) was extracted with a single theoretical stage at a chosen two-phase ratio of 3:1, and the separation factor β_Mn/Co was as large as 65.5. In the subsequent stripping step, more than 99% of manganese from loaded phase was easily stripped under optimal conditions. The microextraction approach greatly enhances the mass transfer while enabling a continuous and controllable extraction process within a simple structure design. When extracting spent electrode material with microextractors, the comprehensive recovery of mangenese can reach 96%. The microextraction approach has a good applicability in the spent lithium-ion battery cathode materials recycling at both bench and industrial scales.

在本文中，我们提出了一种微萃取方法，用于使用皂化二（2-乙基己基）磷酸体系模拟废锂离子电池正极材料的浸出液，从硫酸盐溶液中提取和分离 Mn(II) 和 Co(II)。以下操作变量的影响进行了研究：平衡pH，三Ñ磷酸正丁酯浓度、皂化速率、两相比和停留时间。结果表明，微萃取器可以在 20 s 内达到萃取平衡，从而与传统工艺相比大大减少了必要的萃取时间。体积传质系数比批式装置大 8-21 倍。在微萃取器的帮助下，在选定的两相比为 3:1 和分离因子β _{Mn/Co 下}，95% 的 Mn(II) 被萃取高达 65.5。在随后的汽提步骤中，负载相中 99% 以上的锰在最佳条件下很容易被汽提。微萃取方法极大地增强了传质，同时在简单的结构设计中实现了连续和可控的萃取过程。用微萃取器萃取废电极材料时，锰的综合回收率可达96%。微萃取方法在实验室和工业规模的废锂离子电池正极材料回收中具有良好的适用性。