  Subject of this work is to investigate the kinetics of mass transfer of
volatile amphiphiles from their vapors to aqueous drops, and from the saturated
aqueous drop solutions to air. The used amphiphiles are benzyl acetate,
linalool, and citronellol. The adequate theoretical processing of the
equilibrium surface tension isotherms is applied to construct the
two-dimensional equation of state, which relates the surface tension to the
adsorption at the interface. The measured surface tension relaxations with time
in the regimes of adsorption from vapor and evaporation from drop combined with
the equations of state provide quantitative information on the change of
adsorption because of the volatile amphiphile mass transfer across the surface.
The theoretical analysis of the diffusion and barrier mechanisms in the case of
adsorption from vapor to the aqueous drop shows that the mixed
barrier-diffusion control in the vapor and diffusion control in the drop
describe experimental data. The obtained values of the adsorption rate
constants are six orders of magnitude larger than those for hexane and
cyclohexane reported in the literature. The regime of evaporation from aqueous
amphiphile solution drop follows the convection-enhanced adsorption mechanism
with desorption rate constant in the vapor affected by the simultaneous water
evaporation and amphiphile desorption. The water evaporation suppresses the
evaporation of linalool and accelerates desorption of benzyl acetate and
citronellol. From viewpoint of applications, the obtained physicochemical
parameters of the studied three fragrances can help for better understanding of
their performance in shampoo systems and perfumes. From theoretical viewpoint,
the result show that by introducing an effective amphiphile desorption rate
constant it is possible to quantify the complex volatile amphiphile desorption
accompanied with the water evaporation.
