Separation of Lithium Ion from Lithium-Cobalt Mixture using Electrodialysis Monovalent Membrane

Abstract

Electrodialysis is a separation process which ions are transported through semi permeable membranes under an influence of electric potential. In this research, electrodialysis using monovalent ion exchange membranes was applied to separate lithium ions from mixtures of lithium-cobalt aqueous solution. The study aims to examine factors that affect the performances of electrodialysis monovalent membrane, such as applied voltage, flow rate and the concentration of cobalt as co-ion. The research was conducted using electrodialysis PC cell BED 64004, monovalent cation exchange membrane (PC-MVK) and  monovalent anion exchange membrane (PC-MVA) produced by PCA-PolymerchemicAltmeier, GmbH, Heusweiler, Germany. The effect of applied voltage was studied by varying the voltage in the range of 1 ‑ 4 volt/cell volt. The effects of flow rate and initial concentration of ion were studied by changing the flow rate (10, 15, and 20 L/h) and varying the ratio of initial concentration between Li and Co ions (100 - 100, 100 - 400, and 100 - 500 mg/L). The results exhibited that the highest separation capacity of lithium (99.40%) was obtained when using the optimum applied voltage of 2 volt/cell. Low energy consumption would be obtained when using a low voltage for the process separation. The optimum flow rate for the lithium separation using electrodialysis monovalent membrane in this research was 15 L/h. The greater flow rate reduced the current efficiency and increased the energy consumption. When the concentration of cobalt were increased in the range of 100 - 500 mg/L, the results indicated a decrease of current efficiency but an increase of energy consumption showing the influence of concentration of cobalt to transportation of lithium ions and selectivity of monovalent membrane.