Shen Wang,Meng Rong,Lin-Bing Sun,Yunze Zhao,Huifang Xing,Liangrong Yang
Indeed, the efficient and sustainable recovery of lithium from highly concentrated sodium-containing mother liquors of Li 2 CO 3 and salt-lake brines remains a significant challenge. Herein, two typical Li + recognition receptors, namely benzo-12-crown-4 and thenoyltrifluoroacetone, were separately introduced into the cationic and anionic parts to successfully synthesize novel bi-functionalized task-specific ionic liquids [(B12C4)C n im][TTA] (n = 4, 6, 8). A new, green, and high-efficiency extraction system has been developed by dissolving [(B12C4)C 6 im][TTA] in commercial room-temperature ionic liquid 1-hexyl-3-methyl-imdazolium bis(trifluromethylsulfonyl)imide [C 6 mim][NTf 2 ], without the addition of any other co-extractants. The newly developed [(B12C4)C 6 im][TTA]-[C 6 mim][NTf 2 ] extraction system exhibited a wide pH working range (4.0–11.0), high lithium extraction efficiency (95.4 %), as well as superior separation factors of Li/Na (β Li/Na = 2154.0) and Li/K (β Li/K =757.2). The extraction mechanism involving cation exchange was determined through slope analysis, ion chromatography, UV–vis spectroscopy and FT-IR spectra measurement, indicating that one [(B12C4)C 6 im][TTA] molecule can interact with two lithium ions and form a 1:2 complex. Moreover, the [(B12C4)C 6 im][TTA]-[C 6 mim][NTf 2 ] extraction system also demonstrated fast extraction kinetics, facile stripping and regeneration, along with good cycling performance. Furthermore, a multi-stage countercurrent extraction process to extract lithium from the simulated mother liquor of Li 2 CO 3 was evaluated. When the volume ratio (O/A) of oil phase (O) to water phase (A) was 1.0, only two theoretical extraction stages were needed to extract 91.4 % of lithium into the organic phase. Thus, the [(B12C4)C 6 im][TTA]-[C 6 mim][NTf 2 ] extraction system is promising for lithium extraction from mother liquor of Li 2 CO 3 and salt-lake brines. This study also opens the avenue for designing cationic and anionic bi-functionalized ionic liquids for metal ion separation.
Zhiyu Zhao,Lianjing Mao,Tianyu Zheng,Xiao Li,Chunsen Ye,Pengrui Zhang,Huifang Li,Wei Sun,Jinhe Sun
Enriched lithium isotopes (6Li and7Li) are essential in the nuclear energy industry, where6Li is bombarded with neutrons to produce tritium for fusion reactions, while7Li is used as a core coolant and pH regulator. Separation of6Li and7Li by electromigration is a promising method for producing enriched lithium isotopes that fulfill industrial needs. In this work, based on a previously proposed biphasic system electromigration routine, a three-stage system of ‘LiCl aqueous solution (anolyte)|B12C4-[EMIm][NTf2] organic solution|NH4Cl aqueous solution (catholyte)’ was constructed and the rules of lithium isotope separation and lithium-ion migration investigated. It was shown that the isotope enrichment effect of the catholyte was greatly affected by the experimental conditions, while that of the organic solution was less affected. As the B12C4 concentration increased, enhancement of7Li enrichment in the catholyte and6Li enrichment in the organic solution was observed, and α(C/O) and α(O/A) reached 0.975 and 1.018 at B12C4 of 0.5 mol/L. With the increase in current, migration time, and LiCl concentration, the isotope that was enriched in the catholyte trended from7Li to6Li (about 6 mA, 12 h or LiCl of 5 mol/L). Taking lithium-ion transport efficiency and lithium isotope separation effect into consideration together, a current of at least 6 mA, duration of at least 12 h, LiCl concentration of at least 1 mol/L and B12C4 concentration of 0.2 mol/L are suggested for the electromigration process. The work provides an important reference for system construction and experimental design of a biphasic electromigration separation method, which is expected to be an industrial alternative because of its environmental protection and high efficiency.
危险品化学品经营许可证（带存储）