Hydration and anomalous solubility of the Bell-Lavis model as solvent

TL;DR

This study explores the solvation and anomalous solubility behaviors of the Bell-Lavis water model, revealing how inert solutes influence solvent structure and identifying a line of minimum solubility linked to density maxima.

Contribution

It demonstrates how inert solutes stabilize solvent structure and uncovers the relationship between solubility minima and density anomalies in the Bell-Lavis model.

Findings

Solute stabilizes solvent structure at low temperatures.

A line of minimum solubility coincides with the density maximum line.

Interacting solutes may shift the solubility minimum to higher temperatures.

Abstract

We address the investigation of the solvation properties of the minimal orientational model for water, originally proposed by Bell and Lavis. The model presents two liquid phases separated by a critical line. The difference between the two phases is the presence of structure in the liquid of lower density, described through orientational order of particles. We have considered the effect of small inert solute on the solvent thermodynamic phases. Solute stabilizes the structure of solvent, by the organization of solvent particles around solute particles, at low temperatures. Thus, even at very high densities, the solution presents clusters of structured water particles surrounding solute inert particles, in a region in which pure solvent would be free of structure. Solute intercalates with solvent, a feature which has been suggested by experimental and atomistic simulation data. Examination of solute solubility has yielded a minimum in that property, which may be associated with the minimum found for noble gases. We have obtained a line of minimum solubility (TmS) across the phase diagram, accompanying the line of maximum in density (TMD). This coincidence is easily explained for non-interacting solute and it is in agreement with earlier results in the literature. We give a simple argument which suggests that interacting solute would dislocate TmS to higher temperatures.