The separation and extraction of a phenolic compound called p-nitrophenol were studied by aqueous two-phase systems (ATPS). Solubility data were experimentally obtained at ambient temperature using dipotassium hydrogen phosphate, diammonium hydrogen phosphate, and sodium dihydrogen phosphate and polyethylene glycol polymers with molecular weights of 1000 and 4000 g/mol. The tie-lines were also obtained for solvation data. Then, experimental results were correlated with thermodynamic model UNIQUAC. Factors affecting the binodal curves such as salt types and temperature were also investigated. The salting-out ability of salts was studied, and the results showed that dipotassium hydrogen phosphate had the best result. By examining the effect of three temperatures of 298.15, 305.15, and 313.15 K on p-nitrophenol extraction, the percentage of extraction decreased by 6.05%. The percentage of p-nitrophenol extraction decreased with increasing molecular weight of the polymer and increased with increasing the polymer concentration. The highest obtained percentage of extraction was 96.85% in ATPS including dipotassium hydrogen phosphate (30% w/w) and polyethylene glycol 1000 (40% w/w).

Binodal data and the ternary liquid-liquid equilibria (LLE) was experimentally determined at 298.15 K for hydrophilic alcohols (1-propanol or 2-propanol) + salts (Na 2 SO 4 , (NH 4) 2 SO 4 or NH 4 NO 3) + water systems. The salting-out and the phase-forming abilities of the salts and alcohols for the investigated ATPSs were discussed. The salting-out abilities of the investigated salts follow the order Na 2 SO 4 > (NH 4) 2 SO 4 > NH 4 NO 3 , which can be indicated by the location of the binodal curves plotted in mass fraction, the effective excluded volume (EEV), the salting-out coefficient (K s), the size of the ions, and the Gibbs free energy of hydration of the ions. The phase-separation ability of the studied hydrophilic alcohols was discussed on the basis of the dielectric constant and boiling point of the alcohols. The results show that the phase-separation capability of the system consists of different hydrophilic alcohols in the order: 1-propanol>2-propanol. Furthermore, the binodal curves of the studied systems were satisfactorily correlated by a nonlinear equation with four parameters. The reliability of the calculation method and the corresponding LLE data was successfully proved by the Othmer-Tobias equation and the Bancroft equation.

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