Solubility and tie-line data for water-phosphoric acid-ester system at T = 298.15 K

Phosphoric acid (PA) is an important inorganic acid which has various scientific and industrial applications. This acid has several uses in production of detergents, agricultural feeds, activated carbon, soaps, and several phosphate fertilizers. Due to the growing market orders for the pure acid in various industries such as food industry and agriculture, its extraction from aqueous solutions is very significant. The liquid-liquid equilibrium (LLE) data for extraction of PA from water are important in evaluation of industrial extraction processes. The accurate tie-line data are needed for efficient separation operations, which can be obtained from direct measurements. In this research, experimental solubility and tie-line data for waterPApropyl acetate ternary system were obtained at 298.15 K and p = 101.3 kPa. The quality of the experimental tie-line data was determined through the Othmer–Tobias and Hand correlation equations. Since the two liquid pairs are completely miscible (wateracid) and (acidpropyl acetate) and one liquid pair (waterpropyl acetate) is incompletely miscible, a type-1 LLE phase diagram was obtained. The experimental tie-line data were compared with those calculated by the UNIQUAC and NRTL thermodynamic models. The experimental distribution coefficients and separation factors were evaluated for this system. The results show the ability of this organic solvent for extraction of phosphoric acid from water.

Extraction; ternary system; Phosphoric acid; ester; UNIQUAC; NRTL model