Activity Coefficients from Vapor-Liquid Interfaces : A Molecular Dynamics Approach for Separation Chemistry

International audienceFor improving hydrometallurgical approaches such as solvent extraction, it is crucial to understand the physical chemistry behind separation chemistry. Solvent extraction of metal cations from an aqueous salt solution into an organic solvent phase with aggregate formation due to the presence of extractant molecules (e.g. DMDOHEMA) can be described by the mass action law and the corresponding equilibrium constant [1]. However, this equilibrium constant, which is important for process modeling, can only be calculated, if the activities of all involved compounds are known. In this work a new simulation method based on molecular dynamics is introduced, which allows the calculation of activities of concentrated solutions in good agreement with experimental findings. This method can be applied to any solvent, as long as the solvent is sufficiently volatile