Polymer pendant ligand chemistry, 4. Recovery of precious metal ions from strongly acidic solution with a polymer-supported o-phenylenediamine hydrochloride ligand
✍ Scribed by Wei Li; Mercedes Coughlin; Robert L. Albright; Richard H. Fish
- Book ID
- 103997797
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 738 KB
- Volume
- 28
- Category
- Article
- ISSN
- 1381-5148
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✦ Synopsis
We report on the synthesis and reactivity of a polymer-supported o-phenylenediamine hydrochloride ligand, PS-PDHC, using macroporous 6% crosslinked polystyrene-divinylbenzene beads. The PS-PDHC ligand was found to be highly selective to AuCI; ions in strongly acidic solutions in the presence of other precious metal ions, PdClf-, PtCIi-, RhCli-, and RuCI:-(selectivity values: 2.5, Au/Pd; 7.5, Au/Pt; 7, Au/Rh; 2.2, Au/Ru) as well as other transition metal ions, Fe3+, Cr3+, Cu '+ Ni2+ and Mn2+. The sorption capacity, selectivity, kinetics of removal and , recovery, and solution isotherms have been determined for AuCI; ions in competition with the above-mentioned metal ions. The relative ease of formation of the anionic complex in 0.5 M HCI, AuCl,, was thought to be the primary reason for its selective ability to bind to the PS-PDHC ligand by an anion-exchange mechanism. Therefore, the effect of the HCI concentration on the kinetics of AuCI; ion removal from solution was also investigated to clearly show that raising the pH from 0 to 5 caused a dramatic decrease in rate. The AuCI, ion can be recovered quantitatively from the PS-PDHC beads using a 5% thiourea solution in 0.1 M HCI, allowing the polymer-supported Iigand to be reused.