Our study, conducted with Dr. Turner's group at the University of Alabama, benchmarked the performance of molecular dynamics (MD) simulations in capturing experimental temperature-swing solvent extraction (TSSE) data. MD can elucidate important molecular-level behavior and thermodynamic properties that can advance our fundamental understanding of TSSE. We studied the equilibrium partitioning of four alkali halide brines with an amine solvent. Interestingly, despite the four alkali halide electrolytes having similar thermochemical properties, the brines exhibited drastically different partitioning behaviors. Generally good agreement between experiments and simulations was observed for trends in water miscibility in the organic phase and amine partitioning into the aqueous phase; however we found MD significantly overpredicts the salt rejection of the organic phase. This study points to the potential mechanistic insights that may be gained by using different model electrolytes in TSSE studies, as well as to the need for the development of improved MD force fields for ionic species to fully leverage on the capabilities of in-silico techniques for understanding biphasic water-amine-salt systems.
