Thermodynamic Properties Data of Ternary System KBr–KH2PO4–H2O at 298.15 K

Abstract

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 = IKBr/(IKH2PO4+IKBr)) 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.