Electrodeposition Behavior Of Extracted Platinum Complex In Phosphonium-Based Ionic Liquids Evaluated By Electrochemical Quartz Crystal Microbalance

It is important to develop solvent extraction and electrodeposition processes for platinum group metals in order to reduce the volume of secondary wastes. In this study, the electrodeposition behavior of the extracted Pt(IV) complex in a phosphonium-based ionic liquid (IL) was investigated by using an electrochemical quartz crystal microbalance (EQCM). The charge transfer reaction Pt(IV) + 2e(-) -> Pt(II) was observed at -0.53 V. The significant increase in the mass change (Delta m) and the apparent molar mass (M (app)) of 193.7, as evaluated by the EQCM, confirmed that the electrodeposition reaction Pt(II) + 2e(-) -> Pt(0) proceeded at -1.65 V in this system. Moreover, consecutive solvent extraction and electrodeposition of Pt metal in Alamine336/IL system were performed at 10 cycles. High extraction percentage (E > 95.1%) and good current efficiency (epsilon > 85.8%) were maintained in the first to sixth cycles. The XPS Pt-4f (7/2) spectrum confirmed that all the electrodeposits were in the metallic state.