Electrolytes, colloidal surface tension

Solutions of soaps and other long-chain Colloidal electrolytes. The surface tension of soaps has been very extensively studied,1 but for the most part the results in the literature are discordant far beyond the usual error of measurement of surface tension. In general the surface tension diminishes rapidly with increasing concentration, reaching a steady, or nearly steady, low value after a certain concentration is reached this concentration is naturally lower the longer the hydrocarbon chain. The variation between the results obtained by different experimenters, and even by the same experimenter under different conditions, may... 

Weissenbom PK, Pugh RJ (1996) Surface tension of aqueous solutions of electrolytes relationship with hydration, oxygen solubility, and bubble coalescence. J Colloid Interface Sci 184 550-553... 

Very great precautions must be taken against accidental contamination of the surface, which cannot be renewed except by removing the bubble or drop, and replacing it by a new one. The method has recently proved useful with metals, and in studying the slow changes of surface tension which take place in solutions of some colloidal electrolytes. 

Figure 4.35. Surface tension-logcurves for CjjDMA cr. The electrolyte concentration Is indicated it is either made up from NaCl ( ) or from HCl (o). Temperature 25°C. (Redrawn from S. Ozekl, M. Tsunoda and S. Ikeda, J. Colloid Interface ScL 64 (1978) 28.)...

Adamson (51) proposed a model for W/0 microemulsion formation in terms of a balance between Laplace pressure associated with the interfacial tension at the oil/water interface and the Donnan Osmotic pressure due to the total higher ionic concentration in the interior of aqueous droplets in oil phase. The microemulsion phase can exist in equilibrium with an essentially non-colloidal aqueous second phase provided there is an added electrolyte distributed between droplet s aqueous interior and the external aqueous medium. Both aqueous media contain some alcohol and the total ionic concentration inside the aqueous droplet exceeds that in the external aqueous phase. This model was further modified (52) for W/0 microemulsions to allow for the diffuse double layer in the interior of aqueous droplets. Levine and Robinson (52) proposed a relation governing the equilibrium of the droplet for 1-1 electrolyte, which was based on a balance between the surface tension of the film at the boundary in its charged state and the Maxwell electrostatic stress associated with the electric field in the internal diffuse double layer. 

Karraker, K.A. and Radke, C.J., Disjoining pressures, zeta potentials and surface tensions of aqueous non ionic surfactant electrolyte solutions theory and comparison to experiment, Adv. Colloid Inter/. Sci., 96, 231-264, 2002. 

Emulsoids differ in several ways from suspensoids they are usually more viscous, not easily precipitated by electrolytes, and usually their surface tension is markedly lower than that of the solvent. They also protect suspensoids from precipitation. Graham (V) said the flow of liquid colloids through a capillary tube is always slow compared with the flow of crystalloid solutions, so that a liquid-transpiration tube may be employed as a colloidoscope. The precipitation of emulsoids by electrolytes follows a different course from that... 

Hu Y-F, Lee H (2004) Prediction of the surface tension of mixed electrolyte solutions based on the equation of Patwardhan and Kumar and the fundamental Butler equations. J Colloid Interface Sci 269 442 48... 

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