Selective extraction of Pt(IV) over Fe(III) from HCl with an amide-containing tertiary amine compound

The separation properties of Pt(IV) over Fe(III) in HCl solutions using N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide)amine (EHBAA) were investigated and then compared with those using the conventional extractant tri-n-octylamine (TOA). Also, the structural analyses of Pt(IV) in both of the aqueous (HCl solution) and organic (EHBAA in n-dodecane-2-ethylhexanol solution) phases were performed with EXAFS spectroscopy. The extractability of Pt(IV) was much higher with EHBAA than with TOA in the studied HCI concentration range (0.2-8 M HCl); additionally, EHBAA selectively extracted Pt(IV) over Fe(III) under the condition of [EHBAA] <= 0.1 M and [HCI] <= 1 M. The Pt(IV) loading capacity of 0.1 M EHBAA was about 9.2 (about 0.05 M). Most of the Pt(IV) extracted with 0.1 M EHBAA from 1 M HCI was stripped with 0.1 M NaOH; the co-extracted Fe(III) was selectively scrubbed with distilled water. The structural studies indicated that the Pt(IV) extracted with EHBAA from 1 M HCl formed an ion-pair complex, [PtCl6].(EHBAA.H)(2). (C) 2017 Elsevier B.V. All rights reserved.