Surfactant-oil-water systems near the affinity inversion. Part XI. pH sensitive emulsions containing carboxylic acids

Surfactant-oil-water systems in which the surface active substance is a mix ture of carboxylic acid and its sodium salt (soap), exhibit emulsion proper ty maps that are consistent with the phase behavior and the general emulsio n phenomenology. However they present specific features such as an extended C+ multiple emulsion region and a skinked A(+) W/O emulsion zone. In this case the aqueous phase pH drives the relative hydrophilicity of the acid/sa lt mixture at interface and plays the role of the most sensitive formulatio n variable. Studied systems contain C10 to C14 carboxylic acid, NaCl brine and a light distillation cut, as well as alcohols.