CRITICAL MICELLE CONCENTRATION DETERMINATION IN BINARY-MIXTURES OF IONIC SURFACTANTS BY DECONVOLUTION OF CONDUCTIVITY CONCENTRATION CURVES

A new method for the determination of critical micelle concentrations, cmc, of ionic surfactants from conductivity measurements has been developed. The method is based on deconvolution into Gaussians of the second derivative of the conductivity/concentration data, followed by two consecutive numerical integrations. In testing this procedure, aqueous decyl-, dodecyl-, tetradecyl-, and hexadecyltrimethylammonium bromide solutions were used. The method has proved to be particularly useful for micellar systems formed of binary mixtures of these surfactants, in which the conductivity/concentration curves do not show any distinctive change in slope. The thermodynamic study of such binary mixtures can be carried out by using the mixture cmc vs composition data. © 1990, American Chemical Society. All rights reserved.