Regularities in the concentration and separation of surfactants in a foam

The theoretical and experimental studies devoted to the regularities of foam adsorption concentration and separation of substances occurring in the liquid phase in molecular, ionic, or micellar form are surveyed. The main characteristics of foam concentration and separation, their analytical dependences on the structural parameters of the foam, and their interdependences are analysed. Quantitative relationships for the characteristics of foam separation with due regard to the influence of foam destruction have been obtained. The dependences of the concentration coefficient on the expansion factor and dispersity of the foam and also on the capillary pressure in polyhedral (dry) foams prepared from solutions of individual surfactants and their mixtures are analysed. The reasons for concentration restrictions (upper and lower limits) of the foam concentration method are discussed. Examples of partial separation of surfactants in a foam and foam chromatography are considered. Brief information on equilibrium displacement and acceleration of chemical reactions in a foam is presented. The bibliography includes 77 references.