No abstract

The hygrometric method is used to determine new thermodynamic data on water activity and saturated aqueous solution of the water/D-Sucrose/ Ammonium Dihydrogen Phosphate (ADP) system in a wide range of NH4H2PO4 molality, ranging from 0.1 to 3 mol.kg− 1, and for various D-Sucrose contents from 0. to 4 mol.kg− 1. Powder X-ray diffraction (XRD) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy were used to characterize the solid state. The Pitzer Simonson-Clegg model (PSC) is used to fit the experimental data of osmotic coefficient obtained from water activities data. The predicted saturated aqueous solutions, with the PSC model, are in good agreement with experimental data. For the concentration inferior to 1 mol.kg− 1, the negative deviation from ideality was shown with increasing the ADP concentrations. The estimated values of the activity coefficient of D-Sucrose, activity coefficient of ADP, and the Gibbs energy of transfer of ADP from water to mixture (water /D-Sucrose) show that both ADP and D-Sucrose exert significant salting-out effects on the aqueous solution.

The OCP Group located in Morocco in Africa is one of the biggest producers of phosphates and fertilizers in the world and delivers products to more than 165 clients on five continents. These products include ammonium and di-ammonium phosphate, sodium phosphate, and others with added micronutrients (potassium–calcium–nitrogen) that are designed to effectively feed degraded soil. OCP has launched a new strategy in Africa called “Green Africa” to transform African agriculture and make it a platform for food production. Therefore, with the aim of developing new fertilizers and increasing the yield of soils and agriculture, we are interested in this work to study the influence of electrolytes on the fertilizer phosphate KBr–KH2PO4–H2O. This system was investigated with our developed hygrometric method at 298.15 K. The thermodynamic parameters of the studied system such as the water activity and osmotic coefficient are determined by measuring the relative humidity at various total molalities from 0.2 mol·kg–1 to about saturation, and for different ionic-strength fractions y of KH2PO4 (y = I KBr/(I KH2PO4+I KBr)) of 0, 1/4, 1/3, 1/2, 2/3, 3/4, and 1. The obtained measurements are compared to four models such the Dinane (ECA), Lin et al., Robinson and Stokes (RS), and Leitzke-Stoughton (LS II) equations. The solubilities of KBr and KH2PO4 in their aqueous mixture are also measured at 298.15 K. The solid state was characterized using powder X-ray diffraction (XRD). The PSC model was used to correlate the results and to predict the solute activity coefficients, excess Gibbs energy, and solubilities of the components in the mixture.

Thermodynamic properties of K 2 HPO 4 /D-sucrose/water ternary solutions were investigated at 298.15 K. Water activity, osmotic coefficient, and electrolyte saturation points are determined by measuring relative humidities in the wide range of K 2 HPO 4 molality (ranging from 0.1 to approximately 5 mol•kg −1 ) and for various D-sucrose contents (0.1, 0.3, 0.5, 1, 2, 3, 4, 5, and 5.5 mol•kg −1 ) in the ternary K 2 HPO 4 /D-sucrose/water system. The solid state was characterized using powder X-ray diffraction (XRD) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) techniques. The obtained data were then analyzed using the Pitzer-Simonson-Clegg (PSC) model to determine several thermodynamic properties. These properties encompass the stoichiometric ionic mean activity coefficient of K 2 HPO 4 , excess Gibbs energy, solubility in aqueous solutions, and the Gibbs energy of transfer of K 2 HPO 4 between water (W) and D-sucrose/water (W+S) mixtures. Furthermore, the interactions among water, D-sucrose, and K 2 HPO 4 are also examined and discussed.