A New Method for Simultaneous Estimation of Micellization Parameters from Conductometric Data

• Published in: Chemistry : a European journal Vol. 10; no. 20; pp. 5000 - 5007
• Main Authors: Jalsenjak, Nenad, Tezak, Durdica
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 11-10-2004; WILEY‐VCH Verlag
• Subjects: aggregation number; analytical methods; conductivity; mass action model; micelles
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200400415

A simple method for determination of the counterion binding parameter (α) and aggregation number (N) from conductivity data is proposed. The method is based on fitting the values of the first derivative of conductivity (κ) versus total surfactant concentration (ct) function according to the equation derived from the mass action model (MAM) by using different conductivity models. Sodium dodecylsulphate (SDS) and dodecyltrimethylammonium bromide (DTAB) were chosen for validation of the proposed method. It was shown that the method gives a fairly accurate values for micellisation parameters of SDS (N=51–64, α=0.74–0.75) and DTAB (N=56–62, α=0.77–0.79), both in good agreement with the literature data. In addition, application of the proposed method does not require the value of the critical micelle concentration (cmc).
Conductivity models: A method for simultaneous determination of the micellar parameters from the conductivity data is proposed. The method is based on fitting the values of the first derivative of conductivity versus total surfactant concentration function, according to the equation derived from the mass action model using different conductivity models. An example of the fit is shown here, open circles represent the experimental data and the line, the calculated values.