Adsorption kinetics of nonanol at the air-water interface: Considering molecular interaction or aggregation within surface layer

摘要

The adsorption kinetics of 1-nonanol at the air-water interface was investigated. A video-enhanced pendant bubble tensiometer was applied for the measurement of equilibrium and dynamic surface tension. Two sets of equilibrium data gamma(C) and gamma(Gamma) (equation of state) and two sets of surface tension relaxations gamma(t), for the adsorption of 1-nonanol onto a freshly created interface and for the desorption out of a suddenly compressed interface, were measured. The data are analyzed by either considering the molecular interaction between the adsorbed molecules or assuming that surfactant molecules form two-dimensional aggregates. Both models fit the equilibrium gamma(C) and dynamic gamma(t) data very well, and similar results are obtained: (i) the adsorption of 1-nonanol is cooperative (from the gamma(C) data) and (ii) the adsorption onto a fresh interface is diffusion controlled (from the gamma(t) data). [References: 33]