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Download fileExtraction Mechanism of Lithium from the Alkali Solution with Diketonate-Based Ionic Liquid Extractants
journal contribution
posted on 2020-09-07, 07:11 authored by Junfeng Wang, Shicheng Yang, Xiaofei Zhang, Yilin Wang, Daoguang Wang, Weichao Li, Muhammad Awais Ashraf, Ah-Hyung Alissa Park, Xingchun LiFour diketonate-based
functional ionic liquids (ILs) with trialkylmethylammonium
([A336]+) cation were synthesized, and the synergistic
extraction systems containing IL and thetrialkylphosphineoxide (TRPO)
were developed to separate Li+ from the solution generated
during the Li2CO3 production by the reaction
of LiCl and Na2CO3. Compared to their precursors
1,3-diketones, over the wide pH range of 1.26–10.17, ILs showed
higher Li+ extractability from the solution with a high
Na/Li mass ratio. Among the four ILs, the IL with 2-thenoyl-trifluoroacetonate
(TTA–) anion showed the best Li+ separation
ability. Under the optimized conditions, [A336]TTA was up to 83.26%,
which was much higher than that of its precursor (71.50%). The results
of slope analysis and characterizations indicated that the extracted
Li+ species using the extraction systems with or without
TRPO were Li2CO3·2[A336]TTA·TRPO and
Li2CO3·4[A336]TTA, respectively. Finally,
a three-stage extraction process was validated, and the recovery efficiency
of Li+ from the solution provided by Qinghai CITIC Guoan
Science and Technology Development Co., Ltd. (CITIC) was up to 97.16%,
indicating that the extraction system of [A336]TTA + TRPO was efficient
for separating lithium from the alkaline aqueous solution.