• Foam bubbles

    Foam bubbles

Foam behavior and foam stability of aqueous surfactant solutions

Studies on the stability of foams

Industrial production and cleaning processes place high demands on the surfactants used. In addition to temperature and pH stability, a defined foam formation and stability behavior is required which covers a broad range of capacities and times.

In many areas, for example in flotation separation methods or in foam cleaning, foams are deliberately generated. In other areas foams have an interfering effect and must be avoided:
They adversely affect mixing processes by the formation of a foam phase, increase the volume to be transported, influence flow properties or result in a poorer end product, for example in painting processes. This is why foamability and foam stability provide important information.

Foamability and stability data used for liquid foams are frequently limited to a particular measuring range. For example, the waiting periods required for Ross-Miles values cannot be observed for unstable foams, because the foam has already broken down completely. In many methods foam generation also cannot be carried out reproducibly, although this is essential for making a user-independent and location-independent comparison of parameters. The Dynamic Foam Analyzer – DFA100 works with foam generation conditions that can be standardized and provides the foam parameters tdev and ttr, which describe stable foams and foams with a very short life using a phase model oriented on the decay process. In this way differentiation is possible between a pure drainage phase, followed by a drainage phase with parallel decay, and finally a third phase in which only decay occurs and in which drainage has been completed.

Our application report investigates three surfactants with low to good foam formation tendencies. The foaming and stability behavior of the surfactant solutions could be characterized by the maximum foam height hmax and the parameter tdev, both measured with the DFA100. Comparative interfacial rheology measurements provided a good correlation between the interfacial rheology parameters and the data from the foam measurements.

Download the full application report here: application report AR267.

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