Pressure dependence of solvation of non-polar solute in simple model of water

TL;DR

This study investigates how pressure, temperature, and solute size influence the solvation of nonpolar molecules in water using a simplified two-dimensional model, revealing two distinct solvation mechanisms.

Contribution

It extends previous work by analyzing the pressure dependence and broader conditions of nonpolar solvation using a simple water model.

Findings

Identified two different solvation mechanisms based on solute size.

Demonstrated the model's ability to predict volume and thermodynamic anomalies.

Showed how pressure affects solvation behavior across different temperatures.

Abstract

We modelled the aqueous solvation of a nonpolar solute as a function of the radius, temperature and pressure. In this study a simple two-dimensional Mercedes-Benz (MB) water model was used in NPT Monte Carlo simulations. This model has previously been shown to qualitatively predict the volume anomalies of pure water and the free energy, enthalpy, entropy, heat capacity, and volume change in order to insert a nonpolar solute into water. Here, we extended the studies of solvation of nonpolar solute to examine the pressure dependence and broader range of temperature and size dependence. The model shows two different mechanisms, one for the solvation of large nonpolar solutes bigger than water and the second for smaller solutes.