ISSN:
1435-1536
Keywords:
Micellar extraction
;
complexation kinetics
;
mixed micelles
;
ultra-filtration
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Micellar particles can solubilize lipophilic extractants similarly to the organic phase in classical biphasic extraction. This analogy is used here to investigate the kinetics of complex formation between Ni2+ ions and long chain 5-alkoxypicolinic acids (Cn-PIC, withn=12, 15, 18) solubilized in different types of micelles, namely cetyl trimethylammonium bromide (CTAB), hexaethyleneglycol-dodecylether (C12EO6) and CTAB/C12EO6 mixed micelles. In the case of CTAB micelles, the interaction between the carboxylic function of the extractant and the polar head of surfactant molecules was expected to decrease the rate of complex formation so as to make possible kinetic separation of mixtures of metal ions. The observed rate constants for complex formation at pH 4.5 or 7.0 are indeed much smaller in CTAB micelles than in C12EO6 or mixed micelles, but they still remain too high for the previous purpose, although the influence of the surfactant concentration demonstrates, as expected, a much stronger partitioning in the case of CTAB in comparison to C12EO6. On the other hand, it is shown that, once complex formation has occurred the removal of Ni2+ ions can be achieved using ultrafiltration. The yield of extraction increases withn, with the mole fraction of C12EO6, and with the ligand to metal ratio.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00658691
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