Adsorption properties of C10E8 at the water-hexane interface

A study of the equilibrium and dynamic adsorption properties of octaethylene glycol n-decyl ether (C10E8) has been done by using different tensiometric techniques. The adsorption isotherms have been characterized in the range from 15 to 35 degrees C at both water-air and water-hexane interfaces. In the same temperature range, the partition coefficient in the water-hexane system has been measured, and this allows the estimation of the standard enthalpy of transfer for C10E8. Moreover, the adsorption kinetics at a water-hexane interface has been studied by a capillary-pressure tensiometer. The results indicate that the adsorption properties, at both water-air and water-hexane interfaces, can effectively be described in the framework of a model in which the possibility of different orientations for the adsorbed molecules is considered. This is also in agreement with the results of the adsorption-kinetics experiments at the water-hexane interface, which cannot be described by a diffusion-controlled model with a Langmuir isotherm.