title: Effect of preferential adsorption on the synergism of a homologous cationic surfactant mixture.
abstract: To evaluate the effect of preferential surface adsorption of bromide ions on the synergism of homologous cationic surfactant mixtures reported previously, the surface tension of the aqueous solutions of the hexadecyltrimethylammonium chloride (HTAC)-dodecyltrimethylammonium bromide (DTAB) system was measured as a function of the total molality of surfactants and the relative proportion of DTAB at 298.15 +/- 0.05 K under atmospheric pressure. The excess Gibbs energies calculated from them were -2.6 kJ mol(-)(1) in the mixed adsorbed film and -2.0 kJ mol(-)(1) in the mixed micelle, respectively. A useful analytical procedure to evaluate the composition of individual ions (hexadecyltrimethylammonium, dodecyltrimethylammonium, chloride, and bromide ions) in the adsorbed film and micelle was developed and applied.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. h.matsubara@mbox.nc.kyushu-u.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Matsubara
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakano
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsuda
authors.forename: Takanori
authors.initials: T
authors.lastname: Takiue
authors.forename: Makoto
authors.initials: M
authors.lastname: Aratono