TY - JOUR
T1 - The selectivity of nickel over iron in the lix63-hdnns solvent extraction system
AU - Zheng, Yulian
AU - Osseo-Asare, K.
N1 - Funding Information:
This research was supported by the National Science Foundation
PY - 1985/12/1
Y1 - 1985/12/1
N2 - 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.
AB - 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.
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U2 - 10.1080/07366298508918542
DO - 10.1080/07366298508918542
M3 - Article
AN - SCOPUS:5544219502
SN - 0736-6299
VL - 3
SP - 825
EP - 837
JO - Solvent Extraction and Ion Exchange
JF - Solvent Extraction and Ion Exchange
IS - 6
ER -