Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electronic Resource  (2)
  • 1995-1999  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of metal ion complex formation in micellar media. A comparison between normal and polymerized micelles (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 453-460 
    Details
    ISSN: 1435-1536
    Keywords: Complexation kinetics ; micelles ; polymerized micelles ; micellar extraction
    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 media can be used to investigate the rate of complex formation between hydrophobic extractants and metal ions. Acceleration or retardation effects may be obtained, depending on factors such as the nature of the surfactant, the hydrophilic/lipophilic character and ionization state of the extractant, etc. The present work was aimed at studying the influence of some specific parameters in producing retardation effects, which have potential application for performing separation of metal ions on a kinetic basis. The stopped-flow technique was used to measure the rate of complex formation between Cu2+ and complexing agents with varying alkyl chain length. Micelles made of the nonionic surfactants C12EO6, Triton X-100 and Brij 35 were first considered, which did not show any direct correlation between the rate of complex formation and the thickness of the hydrophilic layer constituted by the polar heads of the surfactant molecules. In a second approach, we have used polymerized micelles obtained from undec-10-enyltrimethyl ammonium bromide, which we assumed to be more rigid than normal micelles. Although the absence of CMC was confirmed, the rates measured in these polymerized micelles were larger than those obtained in micellar solutions of CTAB and DTAB. The results are discussed in relation with the nature of the hydrophobic domains in the different situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652468
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Extraction kinetics and ultrafiltration removal of Nickel (II) by long chain alkoxypicolinic acids in cationic and mixed micelles (1995)
    Springer
    Colloid & polymer science 273 (1995), S. 598-602 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...