A Surface Equation of State for a Partially Soluble Ionized Surfactant

✍ Scribed by Mark W. Vaughn; John C. Slattery

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 167 KB
• Volume: 195
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1997.5129

✦ Synopsis

The surface pressure and adsorption isotherm as functions of surfactant and salt concentration are determined for an ionized surfactant. This analysis differs from previous work in that the surfactant, while ionized in the bulk solution, is assumed to be Here, b { is the mean ion activity coefficient and x ( s ) (i ) is the nonionized at the surface. The analysis is applied to several soluble surface mole fraction of ionized surfactant R or counterion surfactants and provides a reasonable fit to experimental surface Na. These equations contain three parameters which must pressure data. With this analysis, the surface solution is found to be determined experimentally: a ( NaR ) characterizes the distribe ideal for a number of surfactants, so one less parameter is bution of surfactant between the bulk and surface phases, required than is used by the regular solution theory model of DH ( s ) is the heat of mixing of the surface solution, and Lucassen-Reynders (1). ᭧ 1997 Academic Press c ( s )ϱ is the molar density of the surface when saturated with