Electrodialytic Separation of Cobalt and Nickel in the Presence of EDTA (ECC Session)

Cobalt and nickel are toxic heavy metal ions often found in waste solutions from battery recycling and energy product manufacturing facilities. Both are classified as critical materials by the United States and other governments due to their importance in energy technology and national security. However, their similar atomic radii and identical charge makes traditional separation techniques largely ineffective. Prior research has been performed into the selective conjugation of ethylenediaminetetraacetic acid (EDTA) with nickel over cobalt to form an anion to facilitate better electrochemical separation. This study investigates electrodialytic separation in the presence of EDTA as a solution for recovering the critical materials from industrial wastewater solutions.

Using a BED 1-2 electrodialysis bench from PCCell GmbH (Germany), we use various ion exchange membrane configurations to draw the Ni(EDTA) anions out of an acidic solution consisting of equal parts cobalt and nickel and an Ni:EDTA molar ratio of 85:100. The supporting ions are sulfates (sulfuric acid, metallic sulfate hydrates).

Preliminary analysis using inductively coupled plasma optical emission spectroscopy (ICP-OES) shows that over 85% of nickel can be effectively extracted from a solution containing cobalt with this method, with minimal cobalt co-transport. Ongoing experimentation aims to optimize various experimental variables such as membrane selection and current density to increase separation efficiency. EDTA-assisted electrodialysis is a promising strategy for critical metal recovery from industrial wastewater in a potentially scalable and environmentally conscious manner. Recovered materials could then be reused in their respective processes.