Molecular Forces in Liquid-Liquid Extraction

Area of Science:

• Chemical Engineering
• Physical Chemistry
• Supramolecular Chemistry

Background:

• Ion phase transfer is governed by chemical potential gradients, encompassing molecular forces and entropy.
• Solvent extraction involves high-energy, short-range interactions (ion pairing, complexation) and supramolecular/nanoscale organization.
• Modeling is complex due to coupled domains and low free energy of extraction (around kBT) for reversibility.

Purpose of the Study:

• To present and validate the ienaics approach for modeling complex solvent extraction systems.
• To rationalize the free energy of transfer by integrating various energetic and entropic contributions.
• To demonstrate the applicability of the ienaics approach beyond solvent extraction.

Main Methods:

• Quantification by partitioning space into polar cores, interfacial film, and solvent.
• Rationalizing free energy using terms for complexation energies, entropic effects, and solute confinement.
• Applying the ienaics approach to solvent extraction systems and other ionic interfaces.

Main Results:

• The ienaics approach successfully models the coupled domains in solvent extraction.
• Free energy of transfer is explained by a combination of complexation, entropy, and nanoconfinement effects.
• The methodology is adaptable for analyzing membranes and biological interfaces.

Conclusions:

• The ienaics approach provides a robust framework for understanding ion phase transfer in solvent extraction.
• It integrates molecular-level forces with nanoscale organization for accurate free energy calculations.
• This methodology has broad implications for various ionic systems, including biological interfaces.