Extraction and separation of palladium(II), platinum(IV), gold(III) and rhodium(III) using piperidine-based extractants

Abstract

Extraction of palladium(II) from hydrochloric acid media with novel piperidine-based extractants N-decylpiperidine (P-C10), N-dodecylpiperidine (P-C12), N-tetradecylpiperidine (P-C14) and N-hexadecylpiperidine (P-C16) has been investigated. Over 90% of palladium(II) from 0.1M HCl solution can be effectively extracted with P-C12, P-C14 and P-C16 in toluene and the extraction equilibrium is achieved after 10min. Increase in HCl concentration has a negative effect on the effectiveness of palladium(II) extraction. From among the examined stripping solutions the most effective are 0.5M aqueous solution of ammonia and 0.1M thiourea in 1M HCl. The percentage of palladium(II) stripped from loaded organic phase (P-C12) reached nearly 100%. Also the selectivity of palladium(II) extraction over rhodium(III), platinum(IV) and gold(III) with the synthesized N-dodecylpiperidine (P-C12) has been investigated. The selectivity of extraction of palladium(II) over rhodium(III) from 0.1 and 3M HCl with P-C12 was the best. Separation of palladium(II) from platinum(IV) or gold(III) is not so effective and it depends upon the acidity of aqueous solution. N-dodecylpiperidine also shows the extraction ability towards examined noble metal ions in the following order Au(III)>Pd(II)~Pt(IV)>>Rh(III) from 0.1M HCl and Au(III)>Pt(IV)>Pd(II)>>Rh(III) from 3M HCl. Palladium(II), platinum(IV) and gold(III) can be successfully separated through stripping from the loaded organic phase.