Measurement and Correlation of Phase Diagram Data for Several Hydrophilic Alcohol plus Citrate Aqueous Two-Phase Systems at 298.15 K

Binodal data for the ethanol + (NH4)(3)C6H5O7 + water system and the 2-propanol + (NH4)(3)C6H5O7/Na3C6H5O7/K3C6H5O7 + water systems were experimentally determined at 298.15 K. Three empirical equations were used to correlate binodal data. On the basis of the equation with the highest accuracy and lever rule, the liquid-liquid equilibrium data were calculated by MATLAB. The reliability of the calculation method and the corresponding tie-line data was proved by the Othmer-Tobias equation and Bancroft equation. The determined binodal data were also correlated by two theoretical equations on the basis of excluded volume theory. The calculated effective excluded volume (EEV) of salt and the binodal curves plotted in molality both indicate that the salting-out abilities of the investigated salts are in the order Na3C6H5O7 approximate to K3C6H5O7 > (NH4)(3)C6H5O7, and the phase-separation abilities of the investigated alcohols are in the order 2-propanol > ethanol.