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Liquid–liquid equilibrium and tie line data for the nitric acid/phosphoric acid/water/tri-n-octylamine (TOA) system have been determined at 298.15 K for HNO3 mass fractions of 0.028 to 0.26 and H3PO4 mass fractions of 0.00 to 0.19. The distribution coefficients of nitric acid (D1) and water (D3) were studied, and the separation factors β(HNO3/H3PO4) was also investigated. The results show that TOA is very selective, since only small quantities of water and phosphoric acid are present in the organic phase, which indicates the good ability of TOA to extract nitric acid from nitric acid/phosphoric acid mixtures. The experimental tie line data were correlated using the nonrandom two-liquid (NRTL) model. TOA can be used as an effective extractant to separate nitric acid from the HNO3/H3PO4/H2O system.

The ternary system of K2SO4 + KH2PO4 + H2O at (298.15 and 333.15) K was investigated by the method of isothermal solution saturation and moist residues. Thus the solubility data of the system were ...

Liquid−liquid equilibrium and tie line data in the system phosphoric acid/water/tri-n-butyl phosphate/calcium chloride has been determined at 298.15 K, in the concentration range from w = 0.028 to 0.20 phosphoric acid and w = 0 to 0.25 calcium chloride. Distribution coefficients of phosphoric acid and separation factors of water and calcium chloride were determined to establish the extracting capability of tri-n-butyl phosphate. The results show that tri-n-butyl phosphate can serve as an adequate extractant to recover phosphoric acid from dilute phosphoric acid containing calcium chloride.

The densities and viscosities for the tributyl phosphate (TBP) (1) + aviation kerosene (AK) (2) + phosphoric acid (PA) (3) system with the mass fraction of H3PO4 in the range of (0 to 9) % and temperatures from (20 to 60) °C were measured. It is found that the measured viscosities are well-correlated with the temperature and mass fraction of H3PO4 and were fitted to regression equations. The result shows that the effects of the mass fraction of TBP in the mixture (TBP + AK) on the viscosity of the TBP + AK + PA system is in the order of 91.5 % > 82.8 % > 73.7 % under the same temperature and mass fraction of H3PO4, and therefore, it is more appropriate to purify wet-process PA by solvent extraction with a mass fraction of TBP of 82.8 % rather than 91.5 % or 73.7 %.