Effective extraction of Pt(IV) as [PtCl6]2− from hydrochloric acid using a simple urea extractant

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Contributors

Abstract

The conveniently prepared N,N′-dialkylsubstituted urea derivative, 1-butyl-3-(2-ethylhexyl)urea (L), was prepared and elucidated with respect to its performance as an extractant for [PtCl6]2− from HCl solutions. L effectively extracts Pt(IV) and Pd(II) from 0.01 to 10 M HCl solutions with a high selectively over metal ions (Rh(III), Ir(III), Fe(III), Cu(II), Ni(II), Co(II), Zn(II), and Pb(II)) in the concentration range from 0.3 to 1.0 M HCl solutions. According to a slope analysis, the extraction equilibrium reaction of Pt(IV) by L was determined to be [PtCl6]2−aq. + 2Lorg. + 2HClaq. ↔ (PtCl62−)·(HL+)2org. + 2Cl−aq., which is a typical ion-pair reaction. Ultraviolet–visible measurements proved that Pt(IV) was extracted into the organic phase by L as a [PtCl6]2− salt. 195Pt nuclear magnetic resonance (NMR) investigation suggests that the Pt(IV) extracted by L has slightly lower electron density on the Pt(IV) ion compared with the Pt(IV) species extracted by the conventional extractant tri-n-octylamine from HCl solution. Infrared and 1H NMR spectroscopic measurements revealed a strong hydrogen bonding between the Cl− ligands of [PtCl6]2− and the N–H protons of L in the organic phase. Analysis of the water content in the organic phase, before and after the [PtCl6]2− extraction, shows that 0.9–2.6 water molecules are released from the organic phase as the result of [PtCl6]2− extraction from the aqueous into the organic phase by L.

Details

Original languageEnglish
Article number119456
JournalSeparation and purification technology
Volume277
Publication statusPublished - 18 Aug 2021
Peer-reviewedYes

External IDs

Scopus 85112797296
ORCID /0000-0001-7323-7816/work/142257408

Keywords

Keywords

  • Metal recovery, Platinum, Platinum group metal, Solvent extraction, Urea

Library keywords