STUDIES ON THE INTRACTION OF SODIUM CHLORIDE AND DETERGENT

Abstract

Surface-active agents are forming the foam when, they are in the solution form, Foams are Thermodynamically unstable, since their collapse is accompanied by a decrease in total free-energy. However, certain foams will persist for long period, while others break immediately after they are formed. Foams collapse as the r.sult of drainage of liquid in the dubble walls until a portion of the film reaches a thickness of about 50 to l50" 1, when the random motion of molecules is sufficient to cause the sudden breakdown of the film. However, the rate of drainage is not the only factor effecting stability. Perhaps the most important concept, in elucidating the mechanism of foam stability is the surface transport theory of Ewers and Suther land. according to this theory, the surface of a films will flow from a region of low surface-tension to one of high surface-tension. In doing so it will drug underlying water molecules with it. region of low, surface-tension is one in which there is a relatively high concentration of adsorbed surfactant as compered to a high surface-tension area. aqueous solution of pure surfactants in water frequently produce foams which drain rapidly and are unstable. The addition of third component will sometimes greatly increase the stability of the foam. Frequently, the foam is observed to have become slow draining and the surface film viscous. 2 ,-addition of few percent of sodium chloride to the surfactant solution changes the unstable foam to a stable slow draining foam. Based up on these theories and ideas this work has been initiated f,-)r finding the intraction of surfactant and Sodium Chloride, Considering the surface—tension property of the mat rials as a governing factor.