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BACKGROUND: Curcumin is a polyphenol used as a natural colorant or spice with pharmacological properties including analgesic, anti-inflammatory, anticarcinogenic and antioxidant. In this work the partition of curcumin was carried out in an aqueous two-phase system (ATPS) under different conditions. RESULTS: Liquid-liquid equilibrium data for the ATPS composed of 2-propanol + sodium phosphate + water were determined experimentally by the turbidimetric method at temperatures T = 288.15, 293.15, 298.15 and 303.15 K and pH values 4.0 and 5.0. The phase-forming and salting-out capability of the mentioned salt were discussed by determination of the exclusion volume effect (EEV) and salting-out coefficient. The partition of curcumin was carried out. In order to investigate the driving forces that govern the curcumin partition we conducted a thermodynamic study by isothermal titration calorimetry (ITC). The Gibbs free energy transfer ( tr G), transfer enthalpy variation ( tr H) and transfer entropy variation (T tr S) were measured during the dye partition for the systems at 298.15 K.CONCLUSION: The increase in the pH value promoted an increase in the salting-out effect as well as in the exclusion volume value. It was observed that the dye had a strong tendency to transfer to the alcohol-rich top phase, showing K p high values (13.725-112.764). Thermodynamic analysis indicated that curcumin partition in the ATPS at 298.15 K was entropically driven to the top phase. The high values of theoretical recovery, selectivity and partition coefficient obtained in this study show that the investigated systems may be a promising alternative for curcumin pre-concentration and purification.

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