Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

In order to meet the requirements of the market in China for high purified products KH2PO4 and K2SO4, develop a new process to produce more purified KH2PO4 and K2SO4 based on the solvent extraction technology is necessary. Solubility and physical properties data for KCl in the H3PO4 (H2SO4) solution and KH2PO4 (K2SO4) in the H3PO4 (H2SO4) solution at (298.15 and 313.15) K are investigated by the method of isothermal solution saturation. These data can provide a theoretical foundation for the industrial production of KH2PO4 and K2SO4 by the method of solvent extraction. According to the experimental data, corresponding diagrams of solubility and physicochemical properties vs composition are constructed. In these systems, the solubility of KCl decreases from (3.59 to 1.77) mol*kg-1 when the concentration of H3PO4 increases at 298.15K, and decreases from (3.89 to 1.98) mol*kg-1 at 313.15K. The solubility of KCl decreases from (3.59 to 2.63) mol*kg-1 when the concentration of H2SO4 increases at 298.15K, and decreases from (3.89 to 2.90) mol*kg-1 at 313.15K. The solubility of KH2PO4 increases from (1.53 to 2.81) mol*kg-1 at 298.15K and increases from (1.90 to 3.29) mol*kg-1 at 313.15K with the concentration of H3PO4 increasing. The solubility of K2SO4 increases from (0.66 to 1.26) mol*kg-1 at 298.15K and increases from (0.77 to 1.59) mol*kg-1 at 313.15K with the concentration of H2SO4 increasing. The physical properties of the systems change regularly with changing composition of the liquid solution. The measured of the solubility and physical properties diagrams for these systems are instructive to the development of optimizing crystallization process of KH2PO4 and K2SO4.