Separation of Rh(III) and direct electrodeposition in phosphonium-based ionic liquids with electrochemical and spectroscopic analyses for extracted Rh(III) complex

Tokumitsu, Shun*; Matsumiya, Masahiko*; Sasaki, Yuji  

Solvent extraction (SX) of Rh(III) and direct electrodeposition (ED) of Rh metal were carried out in five cycles using phosphonium-based ionic liquids (ILs). The comparatively high extraction performance (70.1%-86.2%) of Rh(III) was stably retained in each SX process. In the subsequent ED process, the electrodeposits were recovered on the cathode and the reasonable current efficiencies (74.9%-85.6%) were achieved in the IL system. The X-ray photoelectron spectroscopy revealed that the electrodeposits obtained during ED process were found to be in the metallic state.