Separation of cobalt(II) from nickel(II) by solid-phase extraction into Aliquat 336 chloride immobilized in poly(vinyl chloride)

doi:10.1016/j.talanta.2006.04.017

Talanta

Volume 71, Issue 1, 15 January 2007, Pages 419-423

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Abstract

A solid-phase absorbent obtained by the immobilization of Aliquat 336 chloride in poly(vinyl chloride) is reported to extract preferentially Co(II) from its 7 M hydrochloric acid solutions containing Ni(II). Under the experimental conditions there was no extraction of Ni(II) which allowed the complete separation of these two ions. Co(II) was rapidly and quantitatively back-extracted with deionised water. A mechanism for the extraction of Co(II) is proposed based on the formation of the ion-pair A⁺[HCoCl₄]⁻ where A⁺ is the Aliquat 336 cation. Fe(III) and Cd(II), usually present in Co(II) and Ni(II) samples, were also extracted into the solid-phase absorbent though at a slower rate than Co(II) and they did not interfere with the separation of Co(II) from Ni(II). It was also demonstrated that this approach allowed the complete separation of Ni(II) from the other metal ions mentioned above.

Introduction

A frequently encountered problem with spectrophotometric [1] and graphite furnace atomic absorption spectrometric [2] methods for the determination of cobalt and nickel when present together is their mutual interference. A suitable method for their separation prior to the analytical measurement is solvent extraction.

Conventional solvent extraction for cobalt recovery from acidic solutions uses various systems including extraction from chloride media with basic reagents such as amines and fully substituted quaternary ammonium compounds, e.g. Aliquat 336 dissolved in diluents like kerosene [3], [4]. One of the challenging aspects of this technology is to design systems that can separate cobalt from nickel because of the chemical similarities of the two elements.

An early paper by Paimin and Cattrall [5] described the solvent extraction chemistry of Co(II) from 4 M and 7 M HCl solutions using Aliquat 336 chloride dissolved in chloroform and they reported high extraction constants for this metal ion. The stoichiometry of the extracted complex was determined and evidence that the Co(II) species extracted had the formulation [HCoCl₄]⁻ was provided by the same authors.

Studies in the field of ion-selective electrodes have shown that Aliquat 336 chloride acts as an excellent plasticizer for poly(vinyl chloride) (PVC) and that stable membranes [6], [7] and beads [8] can easily be formed by dissolving the reagents in tetrahydrofuran (THF) and allowing the THF to evaporate. In addition to the use of such membranes in ion-selective electrodes, there is considerable interest in using PVC-based systems containing appropriate reagents for solid-phase extraction. There are examples in the literature of successful PVC-based solid-phase extraction systems for the separation of metal ions and small organic molecules [9] some of which have emanated from the laboratories of the present authors and their collaborators (i.e., Au(III) [10], [11], Pd(II) [12], Cd(II) [13] and Cu(II) [14]). In some of these studies, the ions of interest were transported across an Aliquat 336 chloride/PVC membrane from a feed to a receiver solution.

It was thus of interest in the present work to evaluate such a solid-phase absorbent for the separation of Co(II) from Ni(II) from their hydrochloric acid solutions without having to use the diluent needed in a conventional solvent extraction system reported by Paimin and Cattrall [5]. Fe(III) and Cd(II) are often present in samples containing Co(II) and Ni(II). For this reason it was also of interest to study the influence of Fe(III) and Cd(II) on the separation of Co(II) from Ni(II).

Section snippets

Reagents

Aliquat 336 chloride (Aldrich, USA) and high molecular mass PVC (Selectaphore, Fluka, USA) were used in the preparation of the solid-phase absorbent membranes. THF (BDH, UK) was HPLC grade. It was further purified by passing it through an activated alumina column to remove the stabilizer and peroxides. Standard Co(II), Ni(II), Fe(III) and Cd(II) solutions, used in the membrane extraction experiments and for calibration purposes, were prepared from CoCl₂·6H₂O, NiCl₂·6H₂O, FeCl₃·6H₂O and CdCl₂

Influence of the HCl concentration on Co(II) extraction

The effect of the concentration of hydrochloric acid on the extraction of Co(II) was studied using the 40% Aliquat 336 chloride/PVC membrane composition. Membranes were in contact with 100 ml of the appropriate HCl solution (1.0–10.0 M) containing 100 mg l⁻¹ Co(II) for 60 min which was found to be an adequate time to reach equilibrium. Table 1 shows the percentage Co(II) extracted as a function of the HCl concentration. It can be seen that this percentage increases steadily with increasing HCl

Conclusions

On the basis of the results obtained it can be concluded that Aliquat 336 chloride/PVC solid absorbent membranes provide an attractive alternative to conventional solvent extraction methods for the separation of Co(II) from Ni(II). These membranes show high selectivity for Co(II) in the presence of Ni(II) and allow the separation of these two metal ions in the absence and presence of other base metal ions such as Fe(III) and Cd(II) which often accompany Co(II) and Ni(II) in their samples. The

Acknowledgement

S.D. Kolev and R.W. Cattrall thank the Australian Research Council for project funding under its Discovery Project scheme.

References (17)

S. Akman et al.
Spectrochim. Acta B
(1995)
R.-S. Juang et al.
Sep. Purif. Technol.
(2005)
G. Argiropoulos et al.
J. Membr. Sci.
(1998)
S.D. Kolev et al.
Anal. Chim. Acta
(2000)
L. Wang et al.
J. Membr. Sci.
(2000)
R.S.L.C. Ferreira et al.
Talanta
(1996)
M. Cox
R. Paimin et al.
Aust. J. Chem.
(1983)

There are more references available in the full text version of this article.

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Separation of cobalt(II) from nickel(II) by solid-phase extraction into Aliquat 336 chloride immobilized in poly(vinyl chloride)

Abstract

Introduction

Section snippets

Reagents

Influence of the HCl concentration on Co(II) extraction

Conclusions

Acknowledgement

Spectrochim. Acta B

Sep. Purif. Technol.

J. Membr. Sci.

Anal. Chim. Acta

J. Membr. Sci.

Talanta

Aust. J. Chem.