ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Spectrophotometric Study of the Effect of Univalent Electrolytes on Critical Micelle Concentrations of [1 -(Ethoxycarbonyl)pentadecyl]trimethylammonium, 1-Hexadecylpyridinium, and Dimethylbenzyldodecylammonium Bromides

O. Greksáková, J. Oremusová, M. Vojteková, and F. Kopecký

Department of Physical Chemistry, Faculty of Pharmacy, Comenius University, SK-832 32 Bratislava

Abstract: Critical micelle concentrations of three antimicrobial cationic surfactants, i.e. quaternary ammonium salts [1-(ethoxycarbonyl)pentadecyl]trimethylammonium bromide, 1-hexadecylpyridinium bromide, and dimethylbenzyldodecylammonium bromide were determined by UV spectrophotometry in aqueous solutions. In the case of the first two compounds, the effect of addition of strong electrolytes KF, KCl, KBr, Kl, KSCN, and LiCl, respectively, on the decrease of CMC was also followed. The results were processed in the form of a logarithmic dependence of CMC on the total concentration and the effect of both anions and cations of the added electrolyte was discussed. The UV spectrophotometry appeared to be a useful tool for the determination of CMC's of the order 10^-3 mol dm^-3 or smaller, if the micellizing surfactant cations or at least the corresponding counterions (in this work Br^- and l^-) exhibited convenient spectral parameters.

Full paper in Portable Document Format: 485a300.pdf

Chemical Papers 48 (5) 300–305 (1994)