The selectivity of nickel over iron in the lix63-hdnns solvent extraction system

Yulian Zheng, K. Osseo-Asare

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The effects of the aqueous phase pH and the organic phase HDNNS concentration on the distribution coefficients of Ni and Fe in pure HDNNS or mixed LIX63-HDNNS systems have been investigated. With the mixed extractants, there is antagonistic extraction of iron below pH 1.4 whereas synergistic extraction occurs above this pH. At pH 2.5 and a fixed LIX63 concentration, iron distribution increases markedly in comparison with the oxime-free system and goes through a maximum with increase in HDNNS concentration. A similar behavior is shown by nickel at both pH 1.0 and 2.5. The log DFe versus pH plot gives a curve with a slope of two for the LIX63-HDNNS mixed system, which suggests that iron is extracted in the form of a species with an ionic charge of 2, probably Fe(0H)2+. The extracted complexes are proposed as Ni(H2L)3D2 where all three oxime molecules function as bidentate ligands, and Fe(OH)(H2L3D2 where one of the oxime molecules functions as a monodentate ligand. The Ni/Fe selectivity is high at low pH and changes mainly as a result of variations in the nickel distribution coefficient, but it is low at high pH because of the synergistic extraction of iron.

Original languageEnglish (US)
Pages (from-to)825-837
Number of pages13
JournalSolvent Extraction and Ion Exchange
Volume3
Issue number6
DOIs
StatePublished - Dec 1 1985

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

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