Question

In supercritical fluid extraction, what will be the critical temperature (CT) and critical pressure (CP)?

• A. 34°C and 50 atm
• B. 31.1°C and 73.8 atm
• C. 54°C and 78 atm
• D. 40°C and 60 atm

Hint:

CO$_2$ is the preferred supercritical fluid due to its moderate critical point and safety profile in pharmaceutical processes.

Answer 1

The Correct Option is B

Supercritical fluid extraction (SFE) uses a fluid above its critical temperature and pressure, where it exhibits unique solvent properties between those of liquids and gases. The most commonly used supercritical fluid in pharmaceutical and food industries is carbon dioxide (CO$_2$) because of its relatively low critical temperature and pressure, non-toxicity, and inertness. - The critical temperature (CT) of CO$_2$ is 31.1°C. - The critical pressure (CP) of CO$_2$ is 73.8 atm (approximately 7.38 MPa). Above these conditions, CO$_2$ becomes a supercritical fluid, which can diffuse through solids like a gas and dissolve substances like a liquid, making it an excellent extraction solvent for sensitive compounds without thermal degradation. This critical point is important because: - It allows extraction at relatively mild conditions preserving thermolabile substances. - It eliminates the use of organic solvents, making the process environmentally friendly. - Adjusting temperature and pressure near the critical point allows selective extraction by changing solvent power.