Thermodynamic Consideration of Mixtures of Surfactants in Adsorbed Films and Micelles

✍ Scribed by Makoto Aratono; Masumi Villeneuve; Takanori Takiue; Norihiro Ikeda; Hidemi Iyota

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 218 KB
• Volume: 200
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1997.5369

✦ Synopsis

of total molality m ˆat various mole fractions of surfactants

The thermodynamic relations describing the equilibrium be-X ˆ2, and then the m ˆvs X ˆ2 curve at a given g is constructed. The tween the bulk solution and the adsorbed film were derived for thermodynamic relation, which is developed for the respective two-component surfactant mixtures that do not share common combinations of surfactants without relying on particular ions. The mean activity coefficients in the adsorbed film, which models of mixing, is applied to the m ˆvs X ˆ2 curve to evaluate can be estimated experimentally, were introduced and proven to the compositions of adsorbed film X O H 2 . Then the miscibility comprise a factor attributable to the preferential adsorption of is examined by using the phase diagram of adsorption (the ions. The excess Gibbs energy of adsorption was defined by using m ˆvs X ˆ2 and X O H 2 diagrams at a given g).

the mean activity coefficients and the composition of adsorbed

Recently we have shown that the activity coefficients and film. The equation of ideal mixing of two components in the adsorbed film was also derived. The analogous equations were develexcess Gibbs energy of adsorption and that of micelle formaoped with respect to the equilibrium between the bulk solution tion are estimated by applying the equation describing ideal and the micelles. The equations derived were shown to be easily mixing to phase diagrams, and afford further insight into the converted to those for ionic-ionic surfactant mixtures with commiscibility for nonionic-nonionic (10, 11), cationic-anionic mon ions, and ionic-nonionic and nonionic-nonionic surfactant (12), and cationic-nonionic (13) surfactant mixtures. The mixtures. Furthermore, the equations were utilized for examining purposes of this paper are as follows: first, the thermodynamic the miscibility of surfactants in the decylammonium bromide equations are developed for ionic-ionic surfactant mixtures (DeAB) -dodecylammonium chloride (DAC), decylammonium without a common ion and also for ionic-ionic mixtures with chloride (DeAC) -DAC, and DeAB-DeAC mixtures. ᭧ 1998 a common ion, which are then transformed to equations appli-Academic Press

cable to ionic-nonionic and nonionic-nonionic mixtures. Second, some of the equations developed are employed for three kinds of cationic surfactant mixtures. 0 G H b dm I b 0 G H d dm I d , [1] 161