Thermodynamics of Malonamide Aggregation Deduced from Molecular Dynamics Simulations

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Understanding the aggregation behavior of extractants is crucial for optimizing solvent extraction processes.
• Malonamide extractants are widely used, but their aggregation in aliphatic solvents requires detailed study.
• Molecular dynamics simulations offer a powerful tool to investigate molecular interactions and self-assembly.

Purpose of the Study:

• To investigate the aggregation of malonamide extractants in an aliphatic solvent with varying water content using molecular dynamics.
• To determine the thermodynamic properties of these aggregates, including Gibbs energy and mass action law constants.
• To develop a model for predicting critical micelle concentration and osmotic data.

Main Methods:

• Employed molecular dynamics simulations to study malonamide extractant aggregation.
• Utilized association criteria based on inter-molecular distances and graph theory to analyze aggregate distribution.
• Developed a thermodynamic model incorporating aggregate formation and solution activity.

Main Results:

• Computed aggregate distribution, Gibbs energy of aggregates, and mass action law constants.
• Developed a model to calculate critical micelle concentration and osmotic data for varying extractant concentrations.
• Demonstrated that accurate aggregation modeling predicts thermodynamic behavior, even without explicit organic phase activity correction.

Conclusions:

• The study successfully modeled the aggregation of malonamide extractants in aliphatic solutions.
• The developed model accurately predicts solution thermodynamics, showing good agreement with experimental results.
• Explicit calculation of organic phase activity is not always necessary when aggregation is accurately depicted.