The Electrochemical Deposition of Samarium and Europium Dissolved in Ionic Liquid Solvent

摘要

Rare-earth elements include the lanthanide series in the periodic table with the addition of scandium and yttrium. China produces approximately 95% of the world's rare-earths supply and is the largest consumer of the world's rare earth supply. Domestic production of rare-earth metals is a priority in the US. The domestic demand for rare-earth elements is largely based on their use in electronic devices, catalytic converters, and more importantly defense applications. Therefore, China's monopoly of rare-earth elements is viewed as a threat to national security. Although capital investments have resulted in an increase in domestic mining and refining of rare-earth materials, full scale production will take time. Alternatively, new methods for the reclamation of rare-earth materials could reduce the dependence on imported materials, as well as reduce electronic wastes in landfills. In this thesis, a path for the electrochemical reclamation of rare-earth materials is explored. Specifically, the dissolution of samarium carbonate and europium carbonate are examined in ionic liquid containing the acid N,N-bis(trifluoromethylsulfonyl)imide, HTf2N. The use of carbonate derivatives facilitates the dissolution of the rare-earth species through the formation of carbonic acid. The carbonic acid can then be purged through a decomposition reaction that produces water and carbon dioxide. The dissolution and coordination of the lanthanide with bis(trifluoromethylsulfonyl)imide anion, Tf2N, is evaluated using a spectroscopic method (UV-Vis). The electrochemistry of samarium and europium is examined in the ionic liquid and the studies demonstrate that electrochemical deposition of samarium and europium species occur. SEM/EDX analysis of the deposit on a grafoil electrode confirms the electrochemical reclamation of samarium and europium metal.