Development of deep eutectic liquids that can solve Sm2(CO3)3 and Nd2(CO3)3 and investigation of the response of these carbonates to electrochemical activation

In this thesis, suitable deep eutectic solvents for the leaching process of rare earth carbonates were determined. Physical properties, such as viscosity and conductivity measurements, were performed. Cyclic voltammetry (CV) and chronoamperometry (CA) techniques were applied to get information about the electrochemical behavior of DESs. TGA analysis showed approximately 10% hydrate in the rare earth elements carbonate. The stable potential ranges of bare DESs, and the potentials that carbonate decomposes, were determined via CV and CA techniques applied to the microelectrode. SEM-EDS and XRD analyzes were performed to determine the chemical composition of decomposed Nd and Sm carbonate hydrate powder on the platinum electrode. As a result, it was observed that the rare earth element carbonate hydrates were converted into rare earth element oxides. In order to confirm the effect of electrocatalytic activation, the leaching efficiency of carbonates was first implemented in bare DES solvents at 55±5 oC for 24 hours with no applied potential. Then the same experimental leaching setup was operated with electrocatalytic activation for 6h. ICP-MS was employed for dissolved rare earth elements. The leaching efficiency was increased by over 100% with applied pulse techniques and electrocatalytic activation.