Question

What are the critical temperatures and pressure values of three different fluids, namely CO2, N2 and Air? Discuss which is more suitable for use in supercritical fluid extraction and why.

Answer 1

fluid	Critical temperature(K)	critical pressure (bar)
Carbon dioxide(CO2)	304.1	72.8
Nitrogen(N2)	126.2	33.5
Air	132.41	37.25

Supercritical fluid extraction:

generally, organic solvents have been used in conventional solvent extraction processes for extraction of foods, fats and in petrochemical processes, polymer processes etc. But these solvent extraction are become cause for pollution of land, air and water. To avoid these pollution problems a newer technology was emerged with concern of free pollution of environment , that is Supercritical Fluid Extraction process.

Supercritical fluid is termed as it is neither gas nor liquid but combined properties of gases and liquids in an intriguing manner. These are produced by heating of gas above its critical temperature or compressing a liquid above its critical pressure.

CO2 is the most suitable fluid used in supercritical fluid extraction process,sometimes modifies by co-solvents such as ethanol or methanol. extraction conditions for supercritical carbon dioxide are above the critical temperature of 31 degree celsius and critical pressure of 74 bar