High-pressure solubility data of the system resveratrol (3)+ethanol (2)+CO 2 (1)

Abstract

Supercritical fluid extraction possesses several advantages over traditional liquid-solvent-based extraction methods, including improved selectivity, expeditiousness, automation and environmental safety. Fluid-phase equilibrium data are essential for studying the viability of supercritical extraction and the design of the extraction columns often used for this type of separation. Resveratrol has been correlated with serum lipid reduction and inhibition of platelet aggregation, and its cancer chemopreventive activity has recently been reported. The extraction of resveratrol using supercritical CO 2 is not possible; it only extracts traces of product, probably due to its polar nature. So, it is necessary to use a co-solvent. Ethanol is appropriate because it is a polar solvent permitted in the food industry. This work uses different mixtures of ethanol–CO 2, ranging from 5 to 15% of ethanol, to optimise the amount of resveratrol extracted. The solubility of resveratrol in the supercritical solvent was measured at 313 K and pressures ranging from 80 to 140 bar. In order to correlate the results obtained, two equations of state were successfully used (Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK)). These equations show similar deviations, but PR shows a better correlation with experimental data. The solubility of resveratrol shows a maximum at an intermediate value of percentage of ethanol. It is roughly 7.5% of ethanol. So the optimal concentration of co-solvent was found. This solubility rises with pressure.