Solid–Liquid Equilibrium of GLA-NaCl System and Its Application for Separating GLA and NaCl

To separate and purify glufosinate-ammonium (GLA) and NaCl during the production of GLA, the solid–liquid equilibrium of GlA-NaCl-H2O system at 278.15, 313.15, and 333.15 K and the solid–liquid equilibrium of GlA-NaCl-H2O/CH3OH system at 333.15 K were measured by the isothermal dissolution method. The equilibrium solid phases were determined and characterized by Schreinemaker's wet residue method and X-ray diffraction. The results show that the phase diagram contains one invariant point, two univariate curves, and two single-salt crystallization regions corresponding to GLA and NaCl, respectively. Moreover, the influence of temperature and solvent on the thermodynamic properties of the GLA-NaCl system was investigated. It was found that temperature has little influence on the thermodynamic solubility and crystalline phase area of the GLA-NaCl system, while the solvent effect has an apparent influence. A fraction crystallization technology coupling evaporation crystallization and antisolvent crystallization was proposed to extract NaCl and GLA from a GLA and NaCl mixed solution.