A Kinetic Study of Copper Ion Extraction by Kelex 100 at a Heptane–Water Interface

doi:10.1006/jcis.1996.0635

Journal of Colloid and Interface Science

Volume 184, Issue 2, 25 December 1996, Pages 406-413

https://doi.org/10.1006/jcis.1996.0635 Get rights and content

Abstract

A study of the kinetics of Cu²⁺extraction by 7-(4-ethyl-1-methyloctyl)8-hydroxyquinoline (Kelex 100) has been undertaken in a static transfer cell, where the total concentration of the Cu²⁺–Kelex 100 complex in the organic phase is monitored in situ as the reaction proceeds using attenuated total internal reflectance spectroscopy. The temporal characteristics of the extraction of Cu²⁺from water into heptane could be accounted for using a simple one-dimensional diffusion model coupled with a reaction-limited interaction between Cu²⁺and Kelex 100. Rate constants for the reaction of Kelex 100 and Cu²⁺at a model interface were obtained from stopped flow experiments using a neutral micelle (C₁₂E₈) system. These rate constants were used to model the reaction between Cu²⁺and Kelex 100 at the heptane–water interface.

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Cited by (24)

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The extraction and recovery of cadmium from aqueous solutions has been performed by a method which avoids the use of organic solvents. The method makes use of surfactant micelles in combination with metal complexing agents. The complexed metals are concentrated on the micelle surface and then treated by a ligand-modified micellar enhanced ultrafiltration process (LM-MEUF). Subsequently the metal ions are stripped out of the micelle by addition of weakly acidic solutions of a strong electrolyte. Using the anionic surfactant sodium dodecylsulphate (SDS) and the azo-dye ligand pyridine-2-azo-p-dimethylaniline (PADA) we were able to extract Cd²⁺ from aqueous solution with high efficiency rates (∼99%). Once the metal has been extracted in the micellar pseudo-phase it has been recovered by means of NaCl 0.5 mol dm⁻³ acid solution. This procedure allows cadmium to be recovered from the aqueous solution with a yield of 80%. Moreover, the possibility of Cd(II) recovery in the presence of magnesium or zinc ions has been investigated.
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Citation Excerpt :
A well known method in copper extraction at the present time is to employ an alkylated oxime ligand, for example, from the Acorga series, as the extracting agent. Extraction into a co-existing organic solvent, which contains the extractant, and both complex formation and stripping reactions (to recover the metal ion) have been investigated (Albery et al. [4]; Watarai and Satoh [5]; Watarai et al. [6]; Shioya et al. [7]; Cai et al. [8]; McCulloch et al. [9]; Scamehorn et al. [10]). Although this approach works for copper, it cannot be used with other potentially deleterious divalent cations such as cadmium, since no complex formation takes place with either Acorga P-50 or the parent salicylaldoxime.
There is much interest in industrial chemistry in the selective extraction and concentration of toxic metals from aqueous process streams and liquid wastes. In this paper, the use and scope of two simple ligands pyridine-2-azo-p-dimethylaniline (PADA) and 4-(2-Pyridylazo) resorcinol (PAR) in micellar solution are explored in relation to nickel and cadmium ion extraction. The thermodynamics and kinetics of the complexation reactions of Ni²⁺(aq) and Cd²⁺ (aq) with PADA and PAR are discussed; also the stripping reaction, to re-form the metal ion, which is achieved on addition of H⁺(aq) is investigated. A dramatic enhancement of metal ion extraction ability by the ligands is observed for both systems, the increase in the apparent rate and equilibrium constants for complex formation being of the order of 100. The stripping reaction is rapid for both metal ions. The mechanisms of the various reactions are discussed.

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¹: Present address: St. John's College, University of Cambridge, United Kingdom.

²: To whom correspondence should be addressed.

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Regular ArticleA Kinetic Study of Copper Ion Extraction by Kelex 100 at a Heptane–Water Interface

Abstract

Regular Article
A Kinetic Study of Copper Ion Extraction by Kelex 100 at a Heptane–Water Interface