Consensus on the solubility of NaCl in water from computer simulations using the chemical potential route

Abstract

The solubility of NaCl in water is evaluated by using three force field models: Joung-Cheatham for NaCl dissolved in two different water models (SPC/E and TIP4P/2005) and Smith Dang NaCl model in SPC/E water. The methodology based on free-energy calculations [E. Sanz and C. Vega, J. Chem. Phys. 126, 014507 (2007)] and [J. L. Aragones et al., J. Chem. Phys. 136, 244508 (2012)] has been used, except, that all calculations for the NaCl in solution were obtained by using molecular dynamics simulations with the GROMACS package instead of homemade MC programs. We have explored new lower molalities and made longer runs to improve the accuracy of the calculations. Exploring the low molality region allowed us to obtain an analytical expression for the chemical potential of the ions in solution as a function of molality valid for a wider range of molalities, including the infinite dilute case. These new results are in better agreement with recent estimations of the solubility obtained with other methodologies. Besides, two empirical simple rules have been obtained to have a rough estimate of the solubility of a certain model, by analyzing the ionic pairs formation as a function of molality and/or by calculating the difference between the NaCl solid chemical potential and the standard chemical potential of the salt in solution.

Computational methodology for solubility prediction: Application to the sparingly soluble solutes

“…b) Author to whom correspondence should be addressed: df246@cam.ac.uk carry out "brute-force" direct coexistence simulations. 8,9,[15][16][17] This method has the advantage of simplicity, but it generally requires long simulations (in some cases up to microseconds) to achieve solubility equilibrium, even for highly soluble compounds.…”

“…[14][15][16][17][18][19][20] The alternative "thermodynamic" approach determines the saturation solute composition by imposing the chemical potential of the solid phase to the solution in a grand canonical style. Such a route has been followed in the osmotic ensemble method/OEMC/OEMD.…”

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations

“…The former is due to the decrease of the potential energy of the interlayer solution caused, as in the bulk phase, 39 by adding the ions into the pyrophyllite pores while the latter is caused by decrease of the potential energy of the interlayer solution (which is more pronounced at higher salt concentrations) and the change of the interactions of the clay layers and the compensating Na + when the ions were added to the Na-MMT pores.…”

“…For the slightly hydrophobic pyrophyllite pores, the almost linear decrease of ∆U H and ∆U solution when m increased is due to adding the ions into the pores which in turn, and similarly as in the bulk phase, 39 decreased the potential energy of the interlayer solution. For the hydrophilic Na-MMT pores, adding the ions into the pores on the one hand decreased the potential energy of the interlayer solution and on the other FIG.…”

Challenges in the use of atomistic simulations to predict solubilities of drug-like molecules

“…We are aware of three main approaches to compute the solubility of solids in solution using physical approaches: ECM-based methods 21, 23 , EMM-based methods 22, 51, 55 , and the approach of Michael Schnieders and collaborators which computes sublimation and solvation free energies and uses these in an alternate thermodynamic cycle to obtain solubility estimates 15, 56 .…”