Phase Equilibrium Data of Ternary Mixtures (Water + Orthophosphoric Acid + Chlorinated Methanes)

Abstract

In the present study, phase equilibrium data of the systems (water + orthophosphoric acid + chlorinated methanes) were measured in the temperature range of 298.2−318.2 K under ambient conditions. Chloroform and carbon tetrachloride were chosen as chlorinated solvents. Both the systems exhibited a type II phase behavior. The presence of hydrogen atoms in chloroform caused differences in phase behavior, partition coefficients, and solubility of the acid in the studied chlorinated methanes. Solid orthophosphoric acid was dissolved six times more in chloroform than in carbon tetrachloride. The thermodynamic modeling was conducted using the NRTL and UNIQUAC equations. Root mean square deviations were calculated to assess the quality of correlations, and the values were lower than 1% for UNIQUAC and 2% for NRTL models. The binary interaction parameters were optimized, and the temperature dependency of the binary parameters was considered. The performance of the studied solvents was evaluated by calculating the distribution coefficients (0.007 to 0.032 for chloroform and 0.004 to 0.008 for tetrachloromethane as solvents) and separation factors (9.81 to 1.25 for CHCl 3 and 5.67 to 1.70 for CCl 4 solvent systems) over the immiscibility region. Temperature increment had obvious effects on the partition coefficients of chloroform ternary mixtures. The obtained partition coefficients at 298.2 K were eventually regressed using the Catalań linear solvation energy relationship (LSER) model. The LSER modeling proposed that polarizability and dipolarity have large negative and positive effects on the distribution coefficient, while acidity and basicity have small and very small positive effects, respectively. LSER modeling of separation factors suggested polarizability as the strongest positive function and basicity as a negative one.