Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature

Abstract

This work was to investigate the lithium ion fractionation from various binary cation systems at various operating temperatures by electrodialysis (ED) with monovalent selective ion exchange membranes (usually called selective-electrodialysis, S-ED). Then a ternary cation system was selected to verify the results obtained from the binary cation systems. In Li+–Mn+ (Mn+: Na+, K+, Mg2+, Ca2+) brines containing only one kind of anion-Cl−, higher efficient recovery of lithium was obtained at higher temperature than at lower one, and the separation coefficients (FM–Li) at the same lithium recovery ratio were found to be changed slightly with temperature ranging from 10°C to 30°C. The results indicate the relationship between transport enhancement/interionic separation effects and temperature could be preliminarily expressed by Arrhenius-type equation. Moreover, the pore size of membrane and the cationic hydration number were analyzed with temperature increase, and then that FM–Li had little variation caused by temperature was explained. It should attribute to the swelling of membrane and a small reduction of cationic hydration numbers. Further verification was done in Li+–Na+–Mg2+ cation system, and the same results were obtained. The investigation experimentally demonstrates that S-ED technology is feasible for separating and recovering lithium from brines in different regions with different environment temperatures.