Extraction and Separation of Precious Metals by a Column Packed with Divinylbenzene Homopolymeric Microcapsule Containing Tri‐n‐octylamine

Abstract

The separation of palladium, platinum, and gold was investigated using a column packed with divinylbenzene homopolymeric microcapsules containing tri‐n‐octylamine (TOA). The extraction of precious metals except platinum using the microcapsules progresses by means of the same reaction proposed in a solvent extraction system. The microcapsules also effectively extracted precious metals from an aqueous hydrochloric acid medium in the column operation. The breakthrough point is delayed in the following order: platinum, palladium, and gold. Almost all TOA molecules enclosed in the microcapsules can act on the extraction reaction with precious metals, which was confirmed by the calculation of the concentration of precious metals extracted into the microcapsules based on the breakthrough curve of each precious metal. By selecting the appropriate eluent, palladium, gold, and platinum were successfully eluted from the column using an 8.0 mol/dm³ aqueous HCI solution, a 0.1 mol/dm³ thiourea in 0.1 mol/dm³ aqueous HCI solution, and a 0.5 mol/dm³ ethylenediamine in 0.1 mol/dm³ aqueous NaOH solution, respectively. By feeding the eluent stepwise into the column in this order, the mutual separation of precious metals can be successfully achieved.

Keywords:

• Microcapsules
• Extraction
• Column operation
• Precious metals
• Tri‐n‐octylamine