Removal of chloride from ethylene glycol solution using alumina/zeolite membrane as a physical boundary between the organic and aqueous phases

The permeation of Cl^- ions from a NaCl/ethylene glycol (EG) solution during electrodialysis was investigated using alumina and alumina/zeolite membranes. Voltage changes had very little effect on Cl^- permeation through the alumina membrane, suggesting that the driving force for the permeation was concentration-gradient-induced diffusion, and not the electric field. Solvation of the Na⁺ ions by EG resulted in EG migration through the membrane. Replacement of the deionized water (electrolyte) in the anodic cell with NaOH resulted in increased Cl^- permeation, although a greater amount of EG migrated into the NaOH solution as well. No notable difference was observed in Cl^- permeation through the alumina and alumina/zeolite membranes, but EG migration decreased when using the latter membrane, suggesting that EG migration was prevented by the zeolite layer. The proposed alumina/zeolite membrane is, hence, useful for solvent recovery by electrodialysis, but its mechanical stability must be improved for industrial applications.