Efficient Extraction of Phosphoric Acid with a Trialkyl Amine-Based Solvent Mixture

Abstract

Production of phosphoric acid by using wet process technology in China is challenging due to high impurities (P2O5 present is less than 25 wt %). Extraction of phosphoric acid from such low concentration mixtures needs to be improved. Moreover, the separation of chloride and phosphate ions is also important for the subsequent production of phosphate fertilizers. In this study, an organic solvent composed of trialkyl amine (N235), isoamyl alcohol, and sulfonated kerosene was developed to extract phosphoric acid. Pseudoternary phase equilibria, two phase densities, and the viscosities were determined at 298.15 K and atmospheric pressure. Results show that unlike other common organic solvents, the proposed solvent exhibits relatively higher extraction capacity even at low phosphoric acid concentration (P2O5 less than 25 wt %). The separation factor of chloride and phosphate ions reaches up to 39.45 and is several orders of magnitude lager than other common organic solvents including alcohols, cyclohexane, an...