Temperature dependence of the equilibrium and dynamic surface tension of oxyethylated p-tert. Butyl phenol solutions

A maximum bubble pressure tensiometer has been used to study the equilibriu m and dynamic surface tension behaviour of oxyethylated p-tert. butyl pheno l (PTBP-EO10). The available data in the temperature range 303 K to 333 K m ake it possible to determine the thermodynamic quantities of adsorption and micellization. Comparison of the experimental surface tension isotherm wit h theoretical equations shows that the Langmuir isotherm gives sufficient a greement with experimental data. The adsorption kinetics obtained from dyna mic surface tensions in the time range from a few milliseconds up to a few seconds is well described by a diffusion-controlled adsorption model. With increasing concentration, the agreement between experiment and model is goo d when the initial load of the bubble is considered. This effect is of part icular importance for any surfactant solutions at concentrations above the limit of 10(-3) mol/l. At even higher surfactant concentrations, additional effects may come into play, such as the non-equilibrium state of the adsor ption layer.