Selective recovery of gold, palladium, or platinum from acidic waste solution

Abstract

End-of-life electrical and electronic equipment is the potential secondary resource for economically-viable precious metals (PMs), e.g., gold (Au), palladium (Pd), or platinum (Pt). The hydrometallurgical processes produce acidic leachates during the recovery of PMs from waste sources, while the selective recovery of Au, Pd, or Pt from such a matrix is challenging either due to the chemical similarities of elements or complexities in the sources and matrices. A total of nine solid-phase extraction (SPE) systems, all claimed to designed for separation of PMs from complex matrices, was evaluated at varying solution pH (≤ 2 to 10) based on the selectivity towards Au, Pd, or Pt. The observation was used to develop a technique for selective Au, Pd, or Pt separation from acidic waste solutions using a macrocycle-equipped SPE. The feed solution flow-rates, eluent-type or compositions has been optimized to achieve maximum separation efficiency of the target analytes. The relative affinity of the macrocycles in solid-phase toward the ions (Pd > Au > Pt) is the core phenomenon of the proposed technique, and the host-guest type interaction is expected to be more stable than the resinbased separation processes. Furthermore, application of the macrocycle-equipped SPE system is advantageous regarding economics as it minimizes the impact of coexisting ions in the matrix and provides unaltered separation performance for several loading-elution cycles.

Speciation and quantitation of precious metals in model acidic leach liquors, theoretical and practical aspects of recycling

“…The mixture was stirred at 500 rpm for 24 h prior to filtration on Whatman paper to remove particles. The filtered leach solution (referred to as solution LL A ) was then treated on a solid phase extraction cartridge (Analig® PM 07, GLSciences, Tokyo, Japan) [18][19][20] according to the following procedure: the cartridge was conditioned with 25 mL of a 1 mol/L HCl solution before loading 25 mL of LL A . The sample matrix discarded through the loading step is called solution LL B .…”

Gold Recycling at Laboratory Scale: From Nanowaste to Nanospheres

“…), respectively. [16][17][18][19][20][21][22][23] A mechanochemical approach has also been presented, that require the use of specific equipment. [24] Thus, these approaches are not adequate for the treatment of laboratory scale nanowastes, due to the toxicity of the involved materials and/or the complexity of the methodology.…”

Environmental separation and enrichment of gold and palladium ions by amino-modified three-dimensional graphene

“…Precious metals (Ag, Au, Ru, Rh, Pd, Os, Ir, Pt) have excellent corrosion resistance and highly stable chemical properties and are therefore widely used in various elds including agriculture, biomedicine, jewellery, catalysis, and electronic industries. 1 To date, various methods are available for their separation and extraction such as ion exchange, 2 coprecipitation, re assay, solvent extraction, 3,4 liquid membrane separation, and adsorbent separation, 5 among others. In the past, most of the resin used as a matrix, and resin molecules [6][7][8] were functionalized with chemical groups able to increase their adsorption capacity for precious metals.…”