New Thermodynamic Data for NH4NO3-Sucrose-Water Ternary System: Water Activity, Osmotic Coefficient, Activity Coefficient, Excess Gibbs Energy, Solubility and Transfer Gibbs Energy at 298.15 K

The NH4NO3 (ammonium nitrate) and sucrose (sugar) solution hold significant importance in various domains. Ammonium nitrate is commonly used as a fertilizer in agriculture, providing essential nutrients for plant growth. It can also be used as an explosive under controlled conditions. As a chemical reagent, it is involved in the production of other chemical compounds. On the other hand, sucrose is widely used as a sweetener in food, providing energy and enhancing the flavor of food and beverages. It is also employed in food preservation methods to inhibit bacterial growth. Overall, the NH4NO3 and sucrose solution play a crucial role in agriculture, the chemical industry, and the food sector. We are interested in studying the influence of an electrolyte and a non-electrolyte, such as NH4NO3-Sucrose-H2O, on the properties of a solution. The hygrometric technique was employed to acquire new thermodynamic data related to water activity in saturated aqueous mixtures of the water/D-sucrose/ammonium nitrate (AN) system. This study spans a wide range of NH₄NO₃ molalities, from 0.1 to 6 mol·kg⁻¹, and includes various D-sucrose concentrations between 0.1 and 4 mol·kg⁻¹. The experimental results were then compared with predictions from three modeling approaches: the Dinane model (ECA), the Lin et al. equation, and the Leitzke–Stoughton (LS II) model. Powder X-ray diffraction (XRD) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy were employed to investigate the solid-phase characteristics of the system. The experimental osmotic coefficient data, derived from water activity measurements, were interpreted using the Pitzer–Simonson–Clegg (PSC) model, which provided a satisfactory correlation across the studied concentration range. At AN concentrations below 1 mol·kg⁻¹, the system exhibited increasing negative deviations from ideality. The calculated activity coefficients of D-sucrose and AN, as well as the Gibbs free energy associated with the transfer of AN from pure water to the binary D-sucrose/water medium, suggest that both solutes significantly contribute to salting-out effects in the aqueous phase.