Predicting Solubility of Military, Homemade, and Green Explosives in Pure and Saline Water using COSMO-RS

Abstract

The conductor-like screening model for real solvents (COSMO-RS) has previously been shown to give accurate aqueous solubilities for a range of organic compounds using only quantum chemical simulation data. Application of this method for solid organic explosives, however, faces two difficulties; it requires correction for the free energy of fusion (a generally unknown quantity for these compounds) and it shows considerable error for common explosive classes such as nitramines. Herein we introduce a correction factor for COSMO-RS that is applicable to a wide range of explosives, and requires no data beyond a quantum chemistry calculation. This modification allows COSMO-RS to be used as a predictive tool for new proposed explosives or for systems lacking experimental data. We use this method to predict the temperature-dependent solubility of solid explosives in pure and saline water to an average accuracy of approximately 0.25 log units at ambient temperature. Setschenow (salting-out) coefficients predicted by this method show considerable improvement over previous COSMO-RS results, but are still slightly overestimated compared to the limited experimental data available. We apply this method to a range of military, homemade, and “green” explosives that lack experimental seawater solubility data, an important property for environmental fate and transport modeling.