Polymer pendant ligand chemistry, 4. Recovery of precious metal ions from strongly acidic solution with a polymer-supported o-phenylenediamine hydrochloride ligand
1995; Elsevier BV; Volume: 28; Issue: 1 Linguagem: Inglês
10.1016/1381-5148(95)00087-3
ISSN1873-166X
AutoresWei Li, Mercedes Coughlin, Robert L. Albright, Richard H. Fish,
Tópico(s)Nanomaterials for catalytic reactions
ResumoWe 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 AuCl4− ions in strongly acidic solutions in the presence of other precious metal ions, PdCl42−, PtCl42−, RhCl63−, and RuCl52− (selectivity values: 2.5, Au/Pd; 7.5, AuPt; 7, AuRh; 2.2, AuRu) as well as other transition metal ions, Fe 3+, Cr3+, CU2+, Nit+, and Mn2+. The sorption capacity, selectivity, kinetics of removal and recovery, and solution isotherms have been determined for AuCl4− ions in competition with the above-mentioned metal ions. The relative ease of formation of the anionic complex in 0.5 M HCI, AuCl4− 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 AuCl4− 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 AuCl4− ion can be recovered quantitatively from the PS-PDHC beads using a 5% thiourea solution in 0.1 M HCl, allowing the polymer-supported ligand to be reused.
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