The main aim of this thesis is recovery of lithium ion from a solution with high lithium concentration such as sodium contaminated lithium bromide solutions of absorber chillers. To this aim, developing lithium selective cation exchange membranes (CEMs) for recovery of lithium via electrodialysis process, was investigated. In this study, lithium manganese oxide adsorbent was Design Expert Software (Expert®11) and response surface methodology, synthesized via hydrothermal method and by insertion of cobalt into the spinel structure stability of spinel adsorbent structure enhanced. By using maximizing of the adsorbent capacity and stability simultaneously. All optimum conditions of synthesis (lithium-manganese molar ratio, cobalt-manganese molar ratio, and calcination temperature) were obtained by Experiments in this study were designed by Box-Behnken methodology considering three independent variables each at three levels. In the optimum conditions, the adsorbent has adsorption capacity of 53.52 mg/g, high molar selectivity of 90.32 for lithium over sodium and high structural stability. At the optimum conditions, the adsorbent section, the heterogeneous cation exchange membrane was prepared with Purolite structure was investigated by XRD and BET analysis. In the next cation exchange resin and polyethersulfone polymer. Characterization membrane has better characteristics of lithium flux, selectivity and electrical of the heterogeneous cation exchange membranes showed that the synthesized resistance rather than the commercial heterogeneous cation exchange membranes CEM using the insitu polymerization method. Optimization of the surface modification conditions (molar ratio of of Ralex company (CMH-PES). The adsorbent was inserted to the surface of the homemade heterogeneous monomer to cross linker, wt% of initiator and wt% of adsorbent) to achieve the mol.min -1 .m -2 and the lithium molar selectivity of 32.231 were maximum lithium flux value and selectivity simultaneously in the two-cell electrodialysis setup at 5 volts was done. In the optimum conditions, obtained. Also the lithium ion flux of 0.149 surface modification was performed on FUJIFILM VI-CEM commercial homogeneous cation exchange membrane in the previous optimum conditions. In the surface modification of commercial CEM, the surface of the membrane was chlorinated by using thionyl chloride to give an acceptable adhesion and bonding of acrylic acid to the surface. Using FTAR, FTIR, FE-SEM/EDS and SEM analysis, these modifications were confirmed in CEMs. . In the optimum conditions, the lithium ion flux of 0.29 mol.min -1 .m -2 and the lithium molar selectivity of 95.4 were obtained.
