Selective Electrochemical Separation and Recovery of Uranium from Mixture of Uranium(VI) and Lanthanide(III) Ions in Aqueous Medium.

Separation of uranium (U) from interfering lanthanide ions (Ln) in aqueous medium is important in view of sustainable nuclear power production and remediation of radioactive waste. Separation of U in aqueous medium by electrochemical means is still unexplored. Herein, we report electrochemical separation of U from interfering lanthanides ions in 0.1 M KCl on poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) modified platinum (PEDOT:PSS/Pt) electrode. U in solution commonly exists as uranyl (UO). U separation is achieved in a two step process: (i) UO reduction to insoluble urania (UO) which gets deposited on PEDOT:PSS/Pt in the presence of Ln (La, Ce, and Sm) ions and (ii) oxidation of electrodeposited UO to UO in fresh 0.1 M KCl (pH = 2) solution. Electrodeposition of UO is confirmed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Although, the presence of Ln ions in UOsolution hinders electrodeposition of UO, but application of more negative reduction potential (-0.6 V vs Ag/AgCl) for longer duration (8 h) results in quantitative electrodeposition of UO. Inductively coupled plasma mass spectrometry (ICP-MS) shows that 94% (±10%) recovery of UO is possible from mixed solution of UOand Ln ions on PEDOT:PSS/Pt electrode.