Novel anion exchange membrane for concentration of lithium salt in hybrid capacitive deionization

Novel anion exchange membranes that blocks the co-ions effect and improve the desorption step in hybrid capacitive deionization (HCDI) process have been presented. The membranes were prepared by chemical modification of poly(vinylidene fluoride) by ethylene diamine. To confirm ion exchange character and electrical properties of obtained membranes such methods as FTIR, SEM and EIS were applied. Transport phenomenon was described by Arrhenius and Eyring-Polanyi equations. On their bases, taking into account desorption efficiency, membrane modified for 24 h was selected for the further investigation. Its application to the HCDI system allowed to obtain desorption efficiency at 96% level with over 0.9 current efficiency. The salt adsorption capacity of the system reached over 30 mg per 1 g of electrode. For these reasons the evaluated membrane could be considered as perspective material for salt concentration with electro driven process.