Adsorption kinetics of soluble surfactants and the phase transition model 2. Experimental demonstration of 1-decanol

The idea that surfactants may have purely diffusive adsorption and mixed re-equilibration relaxations is verified experimentally in this study. Dynamic surface tension data of 1-decanol for both adsorption and desorption are compared with the theoretical tension profiles predicted by a phase transition model for the entire relaxation period. The fit is good. The adsorption of 1-decanol onto a clean air-water interface is shown to be a diffusion-controlled process. A diffusion coefficient is obtained from the best fit between the experimental data and the theoretical prediction. The re-equilibration of a compressed interface is verified to be a mixed control process. Adsorption and desorption rate constants are obtained from the fit of the relaxation data. Problems of evaporation and contamination are also discussed.