Analysis of solid-liquid equilibrium behavior of highly water-soluble beet herbicide metamitron in thirteen pure solvents using experiments and molecular simulations

Abstract

Metamitron (MET), a highly water-soluble herbicide for sugar beets, has posed a significant threat to aquatic species due to its high solubility in water; therefore, understanding its solid–liquid phase equilibrium data in different solvents is essential for the future development of more environmentally friendly forms. In this study, the solubility data of MET in 12 pure solvents were determined gravimetrically and analyzed using theoretical methods (primarily Molecular electrostatic potential surface analysis, Hirshfeld surface analysis, Reduced Density Gradient analysis, radial distribution function, and solute–solvent interaction energy) to further investigate the solid–liquid equilibrium behavior. Although MET's high solubility in water contributes to environmental contamination, its value is low in comparison to that of other organic solvents. Four models, including the Apelblat equation, the λh equation, the van't Hoff equation, and the NRTL, were used to examine all solid–liquid equilibrium data, and an ARD% below 5 confirmed its good correlation. The MET solubility data is anticipated to provide solid guidance for the future development of more effective and environmentally acceptable green formulations.