Phase equilibria of supercritical CO2-ethanol-stearic acid ternary system and hydrogen bonding between ethanol and stearic acid

Solubility of stearic acid in supercritical CO 2 with ethanol cosolvent was determined at 308.15 K in the pressure range from 8 to 16 MPa, and the cosolvent concentration ranges from 0 mol% to 4 mol%. The corresponding densities of the fluid phases were also measured. It was observed that ethanol enhances the solubility significantly. The solubility increases with pressure noticeably at lower pressure, especially at lower cosolvent concentrations. The effect of pressure on the solubility is very limited at higher pressures or higher cosolvent concentrations. The hydrogen bonding between ethanol and stearic acid in supercritical CO 2 was also studied using FTIR in order to understand the mechanism of the solubility enhancement by ethanol.