Utilization of Electrodeionization for Lithium Removal

In this work, usage of a hybrid polymeric ion exchange resin and a polymeric ion exchange membrane in the same unit to remove Li⁺ from aqueous solutions was reported. The effects of the applied potential difference to the electrodes, the flow rate of the Li-containing solution, the presence of coexisting ions (Na⁺, K⁺, Ca²⁺, Ba²⁺, and Mg²⁺), and the influence of the electrolyte concentration in the anode and cathode chambers on Li⁺ removal were investigated. At 20 V, 99% of Li⁺ was removed from the Li-containing solution. In addition, a decrease in the flow rate of the Li-containing solution from 2 to 1 L/h resulted in a decrease in the removal rate from 99 to 94%. Similar results were obtained when the concentration of Na₂SO₄ was decreased from 0.01 to 0.005 M. The selectivity test showed that the simultaneous presence of monovalent ions such as Na⁺ and K⁺ did not change the removal rate of Li⁺. However, the presence of divalent ions, Ca²⁺, Mg²⁺, and Ba²⁺, reduced the removal rate of Li⁺. Under optimal conditions, the mass transport coefficient of Li⁺ was found as 5.39 × 10^-4 m/s, and the specific energy consumption was found as 106.2 W h/g LiCl. Electrodeionization provided stable performance in terms of the removal rate and transport of Li⁺ from the central compartment to the cathode compartment.