- 作者: Shi-Yow Lin, Ya-Chi Lee and Ming-Jian Shao
- 中文摘要: --
- 英文摘要: A video-enhanced pendant bubble tensiometer was employed for the study of the adsorption kinetics of nonionic surfactant C12E6. Two dynamic processes in a quiescent surfactant solution were monitored by measuring the relaxation profiles of surface tension: the adsorption onto a clean air-water interface and the desorption out of an overcrowded interface due to a sudden shrinkage of pendant bubble. In addition, two equilibrium data, equilibrium surface tension g c and surface equation of state g (Γ), were measured and used for the determination of adsorption isotherm and model parameters. The adsorption of C12E6 was found to be anti-cooperative from the comparison between equilibrium data and the Frumkin isotherm. The controlling mechanism of the adsorption process changes as a function of bulk concentration, indicating a shift of mechanism from diffusion-control at dilute concentrations to mixed diffusive-kinetic control at more elevated bulk concentrations. The desorption process for C12E6 out of an overcrowded interface was also confirmed to be mixed-controlled. Comparison was made for the entire relaxation period of surface tension data and model predictions. Values of the diffusivity and the adsorption/desorption rate constants of C12E6 were evaluated from these dynamic g (t) profiles. At the end, the spherical effect on studying surfactant adsorption kinetics was discussed.
- 中文關鍵字: --
- 英文關鍵字: --