Dynamic adsorption of surfactants at the gas-liquid interface

Surfactants are used to control the interfacial properties of the gas-liquid and liquid-solid interfaces in flotation. This paper investigates the dynamic adsorption of surfactants at the gas-liquid interface. The dynamic adsorption process was modeled by considering the surfactant mass transfer to the gas-liquid interface by diffusion and the Langmuir and Frumkin adsorption isotherms. The numerical computation was applied to solve the non-linear governing equations. The dynamic adsorption was measured in terms of the dynamic surface tension using the pendant drop method. The theoretical models were compared against the experimental data obtained with non-ionic (Dowfroth 250) and ionic (sodium doderyIbenzene sulfate, SDBS) surfactants. The theoretical results agreed well with the experimental data for SDBS, but not for Dowfrother 250, especially for the initial stage. Reasons for the variation in results are given in the pape