A study of C12E4 adsorption kinetics-considering pendant bubble shape

The adsorption of C12E4 onto a fresh air–water interface was reported to be diffusion-controlled. Hsu et al. applied a video-enhanced pendant bubble tensiometer and obtained the dynamic surface tension (DST) for different C12E4 concentrations [C.T. Hsu, M.J. Shao, S.Y. Lin, Langmuir 16 (2000) 3187]. The entire DST profiles were compared with the theoretical DST from a classical spherical model (CSM). CSM assumes that the effect of pendant bubble shape and the existence of needle on DST were negligible. In this study, the actual shape of pendant bubble and the existence of a needle are considered on generating the theoretical DST profiles. The diffusion-controlled simulation profiles in this work predict the DST data well, but a slight different diffusivity may be resulted. Without considering the existence of needle and bubble shape, CSM underestimates a diffusivity 10–12%. An alternative way for correcting the effect of bubble shape in order to use the simple CSM is also given at the end of this work.