Metal extraction using micellar systems

Finally, micellar systems are useful in separation methods. Micelles may bind heavy-metal ions, or, through solubilization, organic impurities. Ultrafiltration, chromatography, or solvent extraction may then be used to separate out such contaminants [220-222]. 

Another of the new techniques for extractive preconcentration, separation, and/or purification of metal chelates, biomaterials, and organic compounds is based on the use of surfactant micellar systems. 

A new potentially exciting development in this area of extractions concerns the use of different reversed micellar systems in countercurrent extractions of different rare earth metals. A mathematical model was developed in order to help optimize the different parameters of this new mode of extraction (364). This should facilitate the further development and utilization of this approach to metal ion separations. 

The metal ion can conveniently be recovered from the acid micellar solution by ultrafiltration. Ismael and Tondre demonstrated the use of ultrafiltration in the back extraction of metal ions from micellar solutions containing Ni + and Cu + using the extractants 8-hydroxyquinoline (HQ) and an alkylated derivative (Cn-HQ) in the presence of cationic micelles of cetyltrimethylammonium bromide and 1-butanol. Decreasing the pH to pH = 3 led to effective extraction of Ni " in the presence of Cu + but, for Cu + extraction, it was necessary to reduce the pH further to less than 1. It is interesting to note that for these systems cationic surfactant systems were used rather than the anionic systems described previously. 

On the basis of data obtained the possibility of substrates distribution and their D-values prediction using the regressions which consider the hydrophobicity and stmcture of amines was investigated. The hydrophobicity of amines was estimated by the distribution coefficient value in the water-octanole system (Ig P). The molecular structure of aromatic amines was characterized by the first-order molecular connectivity indexes ( x)- H was shown the independent and cooperative influence of the Ig P and parameters of amines on their distribution. Evidently, this fact demonstrates the host-guest phenomenon which is inherent to the organized media. The obtained in the research data were used for optimization of the conditions of micellar-extraction preconcentrating of metal ions with amines into the NS-rich phase with the following determination by atomic-absorption method. 

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