Recovery of Platinum from Concentrated Sodium Chloride Brine by Electrodeposition on Vitreous Carbon

摘要

The voltammetric characteristics of Pt(II) and Pt(IV) have been examined at a vitreous carbon electrode in slightly acidic 3M (approx. 15 wt %) NaCl solutions. Pt(IV) is reduced to Pt(II) at approx. 0 V and Pt(II) is reduced to Pt(0) at approx. -0.5 V vs Ag-AgCl. The rate of deposition of platinum metal at -0.5 V is very low on bare carbon, but increases as the coverage of platinum increases. The potential at which hydrogen is evolved in this medium is approx. -0.85 V. A technique has been tested for the removal of sub-part-per-million levels of platinum from the high-salinity brine by controlled-potential electrolysis using a reticulated, vitreous-carbon, flow-through electrode. However, at control potentials negative enough to begin to electrodeposit the platinum at a significant rate, simultaneous reduction of hydrogen ion reduces the current and energy efficiency to an unacceptable level. (ERA citation 09:018389)