The goal of this study is to investigate if membrane technology can be used to extract and retrieve dilute concentrations of Pd from hydrochloric solutions in a cost-efficient way using electrodialysis. Electrodialysis is an ion exchange membrane process for the separation of different components and species. In the electrodialysis process, ions are selectively transported from the diluted compartment to the concentrated compartment through alternatingly stacked cation and anion exchange membranes. More specifically, cations move through cation exchange membranes toward the cathode, and anions migrate through anion exchange membranes (AEMs) toward the anode as a result of an applied electrical potential difference as a driving force.

The process of Pd with chloride complex separation from hydrochloric acid is studied using AEMs involving quaternary ammonium bases. Salts of quaternary ammonium bases are effective extractants for PGMs. The effects of the polymer concentration, ion exchange capacity and water content of the membranes were determined on the rate of the metal transport. It is shown that an effective recovery of Pd complexes was achieved with different tailor-made AEMs during 3 hour of electrodialysis process. Pd transport through AEMs increased by almost 15% after increasing polymer concentration. However, further increment in polymer concentration caused a decreasing trend of recovery process. Desorption of Pd to the concentrate compartment during electrodialysis was found slowest for AEM including highest IEC. Water transport was also induced more after providing highest IEC which is not desired for up-concentration process of PGM. Resulting membranes displayed excellent acid stability behaviour after 5 months exposure in acidic process solution (pH < 1).