Foaming ability of solutions and foam stability

The foaming ability of solutions, characterised by the volume of the foam generated, depends on the composition (including the various stabilising additives), temperature, way of foam generation and the stability of the foam with respect to internal collapse and foam 

The most defined relation appears to be that between the volume and stability of a foam formed by gas barbotage through a foaming solution [93]. In this case the rate of foaming wF is determined by the difference between the rate of gas supply wc, accounting for the liquid volume wl transformed into a foam per unit time and the volumetric rate of foam collapse wcou. After a certain time a dynamic equilibrium is achieved for foams of low stability, i.e. wF = wcoU. 

Bikerman [13] has proposed the parameter rB as a characteristic of the stability of such foams (this parameter is specified in [94-97]) 

When a foam is produced from a solution of effective foaming agents (surfactants with highly polar groups and long hydrocarbon chain) and concentrations higher than Cw, and the process runs up to total consumption of the surfactant solution, the following relation is fulfilled 

To obtain a stable foam, either the duration of foaming or the volume of the foaming solution should be limited. The foam volume, produced from such surfactants would be 

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