Adsorption and desorption kinetics of C12E4 on perturbed interfaces

Two processes for the mass transport of C12E4 in a quiescent surfactant sol ution were studied: (i) the desorption of C12E4 out Of a suddenly compresse d interface; (ii) the adsorption of C12E4 Onto a suddenly expanded air-wate r interface. A video-enhanced pendant bubble tensiometer was used for the m easurement of surface tension relaxation due to the adsorption or desorptio n of surfactant molecules. Both processes were found to be diffusion-contro lled at dilute concentration but diffusive-kinetic mixed-controlled at more elevated bulk concentration for C12E4 Rate constants of adsorption/desorpt ion were evaluated from the comparison between the surface tension profiles and the theoretical profiles predicted from the Frumkin model. The values of the kinetic rate constants of C12E4 Obtained from these two experiments are nearly the same. A theoretical simulation was also performed to confirm the shifting mechanism (J. Chem. Eng. Jpn. 1996, 29, 634) for C12E4 for bo th desorption and expansion processes.