Dynamic Surface Tension of Solutions of Surfactant Mixtures: 1. Diffusion-Convective-Controlled Adsorption

✍ Scribed by Leonid K. Filippov

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 458 KB
• Volume: 167
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1994.1367

✦ Synopsis

A quantitative theory of the dynamic surface tension for 2 multicomponent mixture of surlactants obeying the Langmuir adsorption isotherms with constant diffusion coefficients in the bulk and in the adsorbed layer is developed for diffusion-controlled and diffusion-convective-controlled adsorption models. The effect of the mutual diffusion in the adsorbed layer and the effect of the convective transfer are estimated in an analytical form for the short-time and long-time approximations. It is concluded that the dynamic surface tension can be described by the diffusion-convective-controlled model. It is shown that the equation (F(\gamma(t))=\log \left[\left(\gamma_{0}-\gamma(t)\right) /\left(\gamma(t)-\gamma_{e}\right)\right]=n \log \left(t / t_{\text {rel }}\right)) is valid over a wide range of time for the multicomponent mixture of surfactants. Because the diffusion-controlled and diffusionconvective-controlled adsorption models are shown to be asymptotical, correlation (n) equals one-half. Simple formulae are derived to calculate the parameters (n) and (t_{\mathrm{rel}}) and the dynamic surface tension over a wide range of time for adsorption isotherms of multicomponent mixtures obeying the Langmuir adsorption isotherms. O 1994 Academic Press, Inc.