Liquid–Liquid Equilibrium Data of Extraction with Tri-n-butyl Phosphate on Phosphoric Acid Containing Sodium Sulfate or Potassium Sulfate

Abstract

Wet-process phosphoric acid is developed with the lack of a quality mineral. More and more research focuses on the purification of wet-process phosphoric acid with solvent extraction method. Liquid−liquid equilibrium data are of important significance in the industrial reality. In this work, equilibria data have been obtained for the two quaternary systems phosphoric acid−sodium sulfate−water−tri-n-butyl phosphate and phosphoric acid−potassium sulfate−water−tri-n-butyl phosphate, which contain concentrations of components and densities and viscosities of the equilibrium phases, and also the varieties of distribution coefficient of phosphoric acid are analyzed. In different systems (phosphoric acid solution with sodium sulfate or potassium sulfate at 303.2 K), the distribution coefficient of phosphoric acid with sodium was found to be higher than that of potassium ion, which demonstrates that the extraction of phosphoric acid with sodium is greater than that with potassium ion. In addition, NRTL model and Pitzer's equation are used to correlate the experimental data. The result shows that it is suitable for both systems and obtains adjustable binary parameters of the NRTL model.

Solubility and Activity Coefficients of Three Triazine-Type Compounds in Various Low Ionic Strength Aqueous Solutions

“…Hence, the model is applicable to solutions of high ionic strength . Moreover, the ion interaction parameters are expressed as explicit functions of ionic strength and need very few parameters to estimate the properties of both single and mixed electrolytes. − …”