(11e) Noble Metal Fission Product Recovery By Electrodeposition in Ionic Liquids

U.S. nuclear power plants “temporarily” house more than 57,000 tons of spent fuel.  This spent fuel is composed of unreacted fuel and, radioactive and non-radioactive fission products.  Nuclear energy processes can become more sustainable by recycling the non-reacted fuel and separating the fission products by half-life classification.  This also significantly reduces the volume of waste that requires long-term sequestration.

Ionic liquids have been proposed as non-flammable, minimally volatile, selective extractant/extractant solvents for the separation of fission products from the aqueous solution resulting from the acid digestion of spent fuel rods.  The extracted fission products must be further separated from the ionic liquid.  This can be done by electrodeposition from the ionic liquid.  Ionic liquids can be used as both the solvent and electrolyte in electrochemical systems.  Many ionic liquids have wide electrochemical potential windows, making electrodeposition from most metals, including many fission products, possible.

In the work presented here, the electrodeposition of noble metals in ionic liquids will be reported.  Noble metals are a small, but valuable component of the fission product waste stream and can be used as model systems to other radioactive fission product systems.  The electrodeposition of noble metals including Pd, Ru and Rh will be reported on.  The impact of the ionic liquid selection and the electrochemical conditions on the electrodeposition efficiency, deposit composition and morphology has been investigated.