Hydrated Ion Clusters in Hydrophobic Liquid: Equilibrium Distribution, Kinetics, and Implications

Area of Science:

• Physical Chemistry
• Chemical Physics
• Materials Science

Background:

• Hydrophilic ions in oil phases can interact with trace water, forming hydrated clusters.
• Understanding these hydrated ion clusters is important for various chemical and physical processes.

Purpose of the Study:

• To elucidate the equilibrium size distribution of hydrated ion clusters in an oil phase.
• To determine the microscopic rates of water adsorption and desorption onto these clusters.

Main Methods:

• Utilizing molecular dynamics simulations to model ion-water interactions in an oil medium.
• Calculating the reversible work of hydration to derive cluster size distribution.
• Evaluating intrinsic rate constants for adsorption and desorption after diffusion correction.

Main Results:

• The size distribution of hydrated ion clusters was determined and found to be relatively constant for larger clusters.
• Microscopic adsorption and desorption rate constants were found to be on the order of picoseconds after accounting for diffusion.
• Reversible work of hydration was nearly constant across different hydration numbers, except for small clusters.

Conclusions:

• The microscopic hydration properties of ions in oil are critical for reactions involving both hydrophilic and hydrophobic reactants.
• These properties significantly influence ion transport and reactivity within the oil phase and at water-oil interfaces.