ABSTRACT
The chemical literature on the physical and colloidal chemistry of surfactants, in both theory and practice, is voluminous. Electrolyte addition causes an increase in both the efficiency of adsorption of ionic surfactants and the effectiveness of adsorption. In 1909, E. Twitchell, who had invented sulfonated fatty acids as fat-splitting catalysts, patented the use of these surfactants in water for the separation of oleic and stearic acids. In addition to considerations of the emulsification performance of the surfactant in the oleic-stearic acid separation, and the various phenomena related to critical micelle concentration, a review of the fundamental adsorption and wetting theories that relate to the separation is pertinent. The inorganic salts increase the specific gravity of the aqueous phase, thus affording more convenient centrifugation of the lower aqueous layer, and also exerting a desirable effect on limitation of overemulsification of the solid stearic acid. The adsorption of the sodium alkyl sulfate surfactant on the stearic acid solid phase is maximized.
