Precipitation of water from aqueous mixtures with addition of hydrophilic ions

TL;DR

This paper investigates how the addition of hydrophilic ions induces water precipitation in aqueous mixtures, revealing ion-stabilized water domains and their dependence on temperature and composition.

Contribution

It demonstrates the conditions under which hydrophilic ions cause phase separation and water precipitation in aqueous mixtures, expanding understanding of ion-induced phase behavior.

Findings

Ion addition stabilizes water-rich domains in mixtures.

Precipitation occurs over wide temperature and composition ranges.

Water domains diminish as interaction parameter approaches critical value.

Abstract

We examine phase separation in aqueous mixtures at fixed amounts of hydrophilic monovalent ions. When water is the minority component, preferential solvation can stabilize water domains enriched with ions. This ion-induced precipitation occurs in wide ranges of the temperature and the average composition where the solvent would be in one-phase states without ions. The volume fraction of such water domains is decreased to zero as the interaction parameter $\chi$ (dependent on the temperature) is decreased toward a critical value for each average composition.