화학공학소재연구정보센터
Canadian Journal of Chemical Engineering, Vol.97, 1589-1595, 2019
Electrochemical and adsorption behaviour of Li+, Na+, K+, Ca2+, and Mg2+ in LiMn2O4/lambda-MnO2 structures
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 LiMn2O4/lambda-MnO2 structures was studied, wherein Na+, K+, Ca2+, and Mg2+ 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, CaCl2, and MgCl2), 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+, Ca2+, and Mg2+ barely interacted with the lambda-MnO2 electrode under the experimental conditions. Based on the experimental results, the Li+ adsorption capacity was determined to be similar to 2 mmol center dot g(-1), and the selectivity coefficients of Li+ for Na+, K+, Ca2+, and Mg2+ were 38.78, 35.63, 29.04, and 120.08, respectively. Furthermore, by using ESIX, the Li+ adsorption capacity of the lambda-MnO2 electrode was 82.8 % of its initial value after 50 adsorption-desorption cycles. Thus, we concluded that ESIX involving an lambda-MnO2 electrode can be used to separate Li+ from brine with excellent selectivity coefficients.