Novel phase-transition behavior in an aqueous electrolyte solution

Jacob, J. ; Anisimov, M. A. ; Anil Kumar, ; Agayan, V. A. ; Sengers, J. V. (2000) Novel phase-transition behavior in an aqueous electrolyte solution International Journal of Thermophysics, 21 (6). pp. 1321-1338. ISSN 0195-928X

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We have investigated the near-critical behavior of the susceptibility of a ternary liquid mixture of 3-methylpyridine, water, and sodium bromide as a function of the salt concentration. The susceptibility was determined from light-scattering measurements performed at a scattering angle of 90° in the one-phase region near the locus of lower consolute points. A sharp crossover from asymptotic Ising behavior to mean-field behavior has been observed at concentrations ranging from 8 to 16.5 mass% NaBr. The range of asymptotic Ising behavior shrinks with increasing salt concentration and vanishes at a NaBr concentration of about 17 mass%, where complete mean-field-like behavior of the susceptibility is observed. A simultaneous pronounced increase in the background scattering at concentrations above 15 mass%, as well as a dip in the critical locus at 17 mass% NaBr, suggests that this phenomenon can be interpreted as mean-field tricritical behavior associated with the formation of a microheterogeneous phase due to clustering of the molecules and ions. An analogy with tricritical behavior observed in polymer solutions as well as the possibility of a charge-density-wave phase is also discussed. In addition, we, have observed a third soap-like phase on the liquid-liquid interface in several binary and ternary liquid mixtures.

Item Type:Article
Source:Copyright of this article belongs to Springer.
Keywords:Aqueous Ionic Solutions; Critical Phenomena; Crossover; Light Scattering
ID Code:27933
Deposited On:13 Dec 2010 08:31
Last Modified:17 May 2016 11:07

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