Preparation of lithium ion-selective cation exchange membrane for lithium recovery from sodium contaminated lithium bromide solution by electrodialysis process

This paper presents the results of an experimental work for preparing a lithium selective cation exchange membrane for recovery of lithium via electrodialysis process from a solution contaminated with sodium ions. To this aim, a homemade heterogeneous cation exchange membrane (CEM) was modified by placing spinel type lithium selective adsorbent particles on its top surface by in-situ polymerization method optimized by using Design Expert Software and Response Surface Methodology (RSM). Also, a composite membrane was prepared by insertion of the selective adsorbent in the matrix of homemade heterogeneous CEM. FTIR, FE-SEM/EDS and SEM analyses were used to confirm the modifications on CEMs. Then, the electrochemical properties of the prepared CEMs as well as lithium ions flux and molar selectivity of lithium relative to sodium ions were determined. The optimized values of lithium ions flux and molar selectivity of lithium relative to sodium for the CEM modified by in-situ polymerization method were 0.149 mol min−1 m−2 and 32.2, respectively. These values were 18.58% lower and 62.3% higher, respectively, in comparison with the values for unmodified homemade CEM. Finally, the results showed that the modified CEM can be used promisingly for recovery of precious lithium ions from contaminated lithium bromide solutions of absorption chillers.