Surface tension and other mechanical stresses therefore cause spherical lamellae to link together so that they share surfaces, and the result is a ‘polyhedral’ foam that is more stable.
Spherical lamellae are not stable because of their high liquid content. Repeating this process results the formation of a matrix of lamellas which produce foam.įoam is stable if the energy of the system is low and the forces within the foam are in equilibrium. If air is introduced into a liquid containing a surfactant, thereby agitating it, the surfactant molecules form a double layer around the gas forming a bubble. It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution.
The term ‘surfactant’ is a blend of ‘surface acting agent’ and was coined in 1950. Surfactants reduce the surface tension of water by adsorbing at the liquid interface. Adsorption is a process that occurs when a gas or liquid accumulates on the surface of a solid or a liquid (adsorbent), forming a film of molecules or atoms. Their formation depends on the presence of surfactants, which are by definition, located at the liquid surfaces. Foam is all around us – it can be in a bubble bath or the head of your freshly poured beer where it is fun or it can be useful in mineral processing, waste water treatment, fire prevention or food processing. But it can also be a nuisance and, for effective potato processing, foam control is vital.įoams consists of a matrix of lamellas which are gases encapsulated with different forms of liquids.
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