Measurement and Correlation of Curcumin Solubility in Supercritical Carbon Dioxide

Curcumin is a natural phenolic pigment extracted from turmeric and has a good pharmacological activity in anti-inflammatory, antioxidant, hypolipidemic, and antitumor. It has been frequently used in drug-loaded microspheres recently. However, the reports on its solubility in supercritical fluids have not been seen yet. In the present study, solubility of curcumin in the supercritical carbon dioxide (ScCO2) was determined using the dynamic equilibrium method. The experimental measurements were performed at temperatures of 35, 45, and 55 °C and pressure range from 8 to 20 MPa. The measured data showed that the solubilities of curcumin were between 1.82 × 10–8 and 1.97 × 10–6 (mole fractin) for the corresponding temperatures and pressures. The effects of temperature, pressure, and with and without ethanol cosolvent on the solubility were investigated. The measured solubilities were calculated and correlated by semi-empirical formulas Chrastil and Mendez-Santiago and Teja models. The results showed that the experimental values of solubility were in good agreement with the theoretical ones, and the average absolute relative deviations (AARD) were 5.88% and 11.68% without cosolvent, and the AARD of the latter was 15.50% with the ethanol cosolvent.