On the effect of electrolytes on the mutual solubility between water and nonionic amphiphiles

Abstract

In this paper we report on an attempt to quantify the effect of electrolytes on the mutual solubility between H20 and simple nonionic amphiphiles. On the basis of the studies by Schneider and co-workers, we have determined the minimum amount of lyotropic salts necessary to enforce phase separation between H20 and 1-propanol (C3E0), as well as the amount of hydrotropic salts necessary to make the upper loop of the system H20-ethylene glycol monobutyl ether (C4Ei) vanish. The results of the first series of experiments are compared with the Hofmeister series. The latter series of experiments demonstrate that the effect of a hydrotropic electrolyte, whether surface active or not, is quite similar to that of a hydrophilic nonionic amphiphile or that of pressure. The significance of these effects for the discussion of the phase behavior of multicomponent liquid mixtures including oil (microemulsions) is noted.

Synthesis of Nanosize Silica in a Nonionic Water-in-Oil Microemulsion: Effects of the Water/Surfactant Molar Ratio and Ammonia Concentration

“…The effect of ammonium hydroxide on the phase equilibria may be interpreted as the result of the competition between hydroxyl ions and the oxyethylene groups of the surfactant for interaction with water molecules; i.e., ammonium hydroxide is acting as a lyotropic salt reducing the mutual solubility between water and surfactant (50). Similar results were obtained by Kon-no and Kitahara (21) who studied the effects of sodium hydroxide and salt additions in NP-8/tetrachloroethylene microemulsions.…”

Effect of the Supporting Electrolyte on the Adsorption of Octanoic Acid at the Mercury/Electrolyte Interface

“…Indeed, the increase due to Br − is larger that that of I − . The reason for this effect could be that I − is a stronger water-structure breaker than Br − (according to the Hofmeister series (14)). This leads to a diminished formation of micelles in solution ("salting in" effect) and surely also hemimicelles at the metal/electrolyte interface.…”

“…The effect of added electrolyte on the mutual solubility between the organic compounds and water is known (Hofmeister); see (14). It is well known that the supramolecular assembly of surfactants is affected by the concentrations and species of electrolytes in solutions.…”

The Effect of Anomeric Head Groups, Surfactant Hydrophilicity, and Electrolytes onn-Alkyl Monoglucoside Microemulsions

“…Driving cp ␤ down in temperature consequently shifts the threephase body of water-oil-nonionic surfactant mixtures to lower temperatures. For C i E j 's, the extent to which NaCl lowers cp ␤ in water-C i E j mixtures depends on the amphiphilic strength of the surfactant, with weaker amphiphiles (C 4 E 1 ) experiencing a far greater effect than stronger amphiphiles (C 12 E 6 ) (37,38). Therefore, the ability of NaCl to lower the temperature range of the three-phase body in water-alkane-C i E j mixtures also depends on surfactant amphiphilicity.…”