Ammonium chloride solid-liquid equilibrium in water-ethanol solutions. Experimental study and interaction parameters fitting for the extended UNIQUAC model

• Data for the Ammonium Chloride + Water + Ethanol SLE is reported. • The effect of temperature on Ammonium Chloride solubility was investigated. • A new set of parameters for extended UNIQUAC model were correlated. Ammonium chloride (NH₄Cl) is widely used in agriculture, medicine, and flame-retardant applications, yet solubility data in mixed solvents remain limited for process design. This work reports new experimental solubility data for NH₄Cl in water–ethanol solutions at 288.15–318.15 K and atmospheric pressure, conditions relevant for energy-efficient separation via solvent-out techniques. Ethanol addition was found to significantly reduce NH₄Cl solubility, highlighting its potential to enhance crystallization and by-product recovery near ambient conditions. The Solid–Liquid Equilibrium (SLE) of the ternary system was modeled using the extended UNIQUAC framework, with newly fitted interaction parameters yielding accurate predictions (mean absolute error < 0.07 mol·kg⁻¹ solvent). To the best of our knowledge, this is the first report of thermodynamic parameters for the NH₄Cl + H₂O + C₂H₅OH system, providing novel data and modeling tools to support industrial crystallization and separation process optimization.