Influence of organic vapors on air/liquid interface properties under static and dynamic conditions

This dataset contains experimental and simulation data related to the physicochemical behavior of rising air bubbles in aqueous surfactant solutions containing saturated n-hexane vapor. Bubble rise velocity profiles were measured in pure water and in salt-free solutions of two surfactants: the nonionic n-octanol and the cationic dodecyltrimethylammonium bromide (C12TAB), across a range of concentrations. These results were compared with corresponding systems without hexane vapor. Dynamic surface tension of stationary bubbles was determined using bubble profile analysis tensiometry. In addition, molecular dynamics simulations were performed to examine molecular adsorption processes at the water interface. For pure water, both experimental measurements and simulations confirmed the adsorption of n-hexane molecules from the vapor phase at the interface, consistent with previous studies, although no significant effect on bubble rise velocity was observed. In surfactant-containing systems, a pronounced coadsorption of surfactant molecules from the liquid phase and n-hexane from the vapor phase was detected. Surface tension isotherms were modeled using a modified Frumkin adsorption framework that accounts for both the ionic nature of C12TAB and the coadsorption of n-hexane. The calculated adsorption free energies correlated with interfacial free-energy profiles obtained from molecular dynamics simulations. Bubble rise behavior was further analyzed in terms of drag coefficients and bubble deformation, revealing unusual velocity features during the dynamic formation of the interfacial adsorption layer.