The thermodynamic treatment of the preceding paper has been extended so as to be applied to the adsorption of ionic surfactant from its micellar solution at the water/air interface. The surface tension of dodecylammonium chloride solution has been measured as a function of temperature at concentrations around its critical micelle concentration (CMC). The derivative of surface tension with respect to temperature has been observed to change abruptly at the CMC and then decrease very slowly with increasing concentration. It has been asserted by comparing the thermodynamic relations with experimental results that the chemical potential of micelle depends only on temperature and pressure in a limited concentration range, and the derivative of the surface tension of micellar solution with respect to temperature is related directly to the entropy change associated with the adsorption of surfactant from the micellar state. The micelle has been concluded to be similar in thermodynamic behavior to the adsorbed film.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry