The universality of solubility divergence effects in multicomponent liquid mixtures

Author

Pauline R. Norris

Date of Award

2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Materials Science

Committee Chair

James Baird

Committee Member

Judith Schneider

Committee Member

Gregory Thompson

Committee Member

Anusree Mukherjee

Committee Member

Seyed Sadeghi

Subject(s)

Critical point, Phase rule and equilibrium, Solubility, Principle of Critical Point Universality

Abstract

Critical point effects have been observed in pure fluids, ferromagnets, substitutional alloys, and in binary liquid mixtures having a miscibility gap. That these systems are disparate, while the phenomena observed are similar, serves as the basis for the statement of the Principle of Critical Point Universality, which governs all critical behavior. The effect of the critical point on solute solubility is readily observed; the solubility diverges towards infinity in the critical region. One finds in the critical region that the slope (∂ln solubility/ ∂ (1/Temperature)) of a plot of ln solubility vs 1/Temperature diverges toward infinity if only one composition variable is held fixed. A system meeting this restriction is said to have F = 3 degrees of freedom. In the case, F = 4 and greater, no critical effect is predicted. We have studied solid solubility in several liquid mixtures under F = 3 conditions. These experiments have included the dissolution of methyl orange indicator in both acidic and neutral binary mixtures, the dissolution of a rhodanine dye in an organic, non-ionizing pair of liquids, the dissolution of titanium dioxide, the dissolution of anthracene sampled in the two-phase region and the dissolution of zinc tartrate under conditions of both F = 3 and F = 4. A divergence was observed in the slope of the plot of ln solubility vs 1/Temperature for all F = 3 systems and absent for the F = 4 system. We find convincing evidence for the assertion that these solubility effects are entirely independent of the details of the underlying chemistry and are members of the class of critical effects. There are long range fluctuations in mass density and properties associated with mass density near critical points of physical systems. In the case of binary liquid mixtures, these fluctuations manifest as fluctuations in composition. Thus, it may be that the lack of dependence of the solubility critical effect on the chemical details of the solute and solvent pair is in some way associated with these fluctuations, which are the common property of all critical systems.

Comments

Submitted ... in the joint tri-campus Materials Science program

Recommended Citation

Norris, Pauline R., "The universality of solubility divergence effects in multicomponent liquid mixtures" (2022). Dissertations. 243.
https://louis.uah.edu/uah-dissertations/243