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 mix ed re-equilibration relaxations is verified experimentally in this stu dy. Dynamic surface tension data of 1-decanol for both adsorption and desorption are compared with the theoretical tension profiles predicte d by a phase transition model for the entire relaxation period. The fi t is good. The adsorption of 1-decanol onto a clean air-water interfac e is shown to be a diffusion-controlled process. A diffusion coefficie nt is obtained from the best fit between the experimental data and the theoretical prediction. The re-equilibration of a compressed interfac e is verified to be a mixed control process. Adsorption and desorption rate constants are obtained from the fit of the relaxation data. Prob lems of evaporation and contamination are also discussed.