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Electrochemical and adsorption behaviour of Li + , Na + , K + , Ca 2+ , and Mg 2+ in LiMn 2 O 4 / λ ‐MnO 2 structures
Author(s) -
Liu DongFan,
Sun ShuYing,
Yu JianGuo
Publication year - 2019
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23370
Subject(s) - electrochemistry , chemistry , inorganic chemistry , adsorption , desorption , manganese , selectivity , redox , analytical chemistry (journal) , qualitative inorganic analysis , cyclic voltammetry , ion , lithium (medication) , brine , ion exchange , electrode , dissolution , nuclear chemistry , catalysis , medicine , biochemistry , organic chemistry , chromatography , endocrinology
Manganese dioxide ion‐sieves are known to be highly efficient lithium adsorbents, owing to their high adsorption capacity and selectivity. However, their manganese dissolution rate during acid desorption is high. Therefore, electrically switched ion exchange (ESIX) was proposed to recover Li + from brine. Cyclic voltammetry results indicated that ESIX could be applied to capture lithium from the Li + ‐containing solutions. Besides, the electrochemical behaviour of Li + in LiMn 2 O 4 / λ ‐MnO 2 structures was studied, wherein Na + , K + , Ca 2+ , and Mg 2+ naturally coexisted with Li + in the brine. No redox peaks were observed between 0.3–1.2 V in the MCl solution (MCl = NaCl, KCl, CaCl 2 , and MgCl 2 ), and the positions of the redox peaks in the LiCl solution were similar to those in the LiCl and MCl mixed solution, indicating that Na + , K + , Ca 2+ , and Mg 2+ barely interacted with the λ ‐MnO 2 electrode under the experimental conditions. Based on the experimental results, the Li + adsorption capacity was determined to be ∼2 mmol · g −1 , and the selectivity coefficients of Li + for Na + , K + , Ca 2+ , and Mg 2+ were 38.78, 35.63, 29.04, and 120.08, respectively. Furthermore, by using ESIX, the Li + adsorption capacity of the λ ‐MnO 2 electrode was 82.8 % of its initial value after 50 adsorption‐desorption cycles. Thus, we concluded that ESIX involving an λ ‐MnO 2 electrode can be used to separate Li + from brine with excellent selectivity coefficients.