Abstract: The Performance of supercritical fluid (SCF) as a solvent can be greatly affected by addition of an entrainer to the system. In this study, the constant volume visual method is used to measure the critical point properties of CO₂+ toluene, CO₂+ cyclohexane, CO₂+ n-butyraldehyde, CO₂+ i-butyraldehyde, CO₂+ methanol and CO₂+ ethanol binary systems. These properties provide a good basis for supercritical extraction and chemical reaction. The relationship between the critical point of CO₂+ entrainer binary system and the critical point of supercritical carbon dioxide has been discussed. The phase behavior of single component system has been compared to that of CO₂+ entrainer binary systems.

Key words: Entrainer, Critical point, Binary system