Dynamic adsorption of sodium dodecylbenzene sulphonate and dowfroth 250 onto the air-water interface

Surface active agents (surfactants) are widely used to control the interfacial properties of the gas-liquid and liquid-1 interfaces in the froth flotation separation process. The dynamic adsorption of the surfactants is critical to flotation which is a kinetics-controlled process. This paper examines the dynamic adsorption of sodium dodecylbenzene sulphonate and Dowfroth 250, which is a commercial mixture of polyglycols used to control the dispersion of air in flotation. The dynamic adsorption process was modelled based on either the diffusion-controlled or kinetics-controlled theories. The numerical computation was applied to solve the non-linear governing equations. The dynamic adsorption of the surfactants was measured in terms of the dynamic surface tension using the pendant drop method. Comparison between the theoretical results and experimental data shows that the kinetics-controlled model for the surfactant adsorption describes the experimental data better for both surfactant systems.