(482b) Modeling of Adsorption Dynamics at Air-Liquid Interfaces Using Statistical Rate Theory (Srt): Non-Ideal Surfaces

A large number of natural, technological and biological processes involve mass transfer at interfaces. Interfacial properties, e.g., adsorption at interfaces play a key role in such processes. The mechanistic understanding of adsorption at interfaces often assumes molecular diffusion in the bulk liquid and subsequent adsorption at the interface. Diffusion is well described by Fick's law, while adsorption kinetics is less understood and commonly described using Langmuir-type empirical equations. In this study, a theoretical model for adsorption dynamics at the air-liquid interface considering non-ideal surface behavior is developed; in particular, a new kinetic equation based on the Statistical Rate Theory (SRT) is derived. The non-ideality at surfaces is manifested either through the net attractive interactions between the chains of the adsorbed molecule or net repulsive interactions among the head groups of the molecules. The solute-solvent interactions at the surface can also invoke non-ideal surface behavior. The surface non-ideality in the model equation is incorporated through the surface activity coefficients. Numerical simulations of the models are carried out. The numerical simulations are validated using the literature reported and the experimentally obtained dynamic surface tensions data. Experimentally dynamic surface tensions are obtained using a pendant drop technique by employing axisymmetric drop shape analysis-profile (ADSA-P) procedure.