Supercritical fluid

Phase diagram for carbon dioxide

Description

A material compressed and heated to a point above its thermodynamic critical point. Supercritical fluids (SCF) have the unique ability to penetrate materials like a gas while also dissolving materials like a liquid. Carbon dioxide and water are the most commonly used supercritical fluids. A temperatures and pressures above the thermodynamic critical point, a material's liquid phase and the gas phase will have equal densities and are indistinguishable.

Synonyms and Related Terms

SCF

Physical and Chemical Properties

Table 1. Critical properties of various solvents (Reid et al., 1987)

Solvent	Molecular mass	Critical temperature	Critical pressure	Critical density
	g/mol	K	MPa (atm)	g/cm3
Carbon dioxide (CO2)	44.01	304.1	7.38 (72.8)	0.469
Water (H2O)†	18.015	647.096	22.064 (217.755)	0.322
Methane (CH4)	16.04	190.4	4.60 (45.4)	0.162
Ethane (C2H6)	30.07	305.3	4.87 (48.1)	0.203
Propane (C3H8)	44.09	369.8	4.25 (41.9)	0.217
Ethylene (C2H4)	28.05	282.4	5.04 (49.7)	0.215
Propylene (C3H6)	42.08	364.9	4.60 (45.4)	0.232
Methanol (CH3OH)	32.04	512.6	8.09 (79.8)	0.272
Ethanol (C2H5OH)	46.07	513.9	6.14 (60.6)	0.276
Acetone (C3H6O)	58.08	508.1	4.70 (46.4)	0.278
Nitrous oxide (N2O)	44.013	306.57	7.35 (72.5)	0.452

Resources and Citations

• Sung Mo Kang, Achim Unger, J.J. Morrell, 'The Effect of Supercritical Carbon Dioxide Extraction of Color Retention and Pesticide Reduction of Wooden Artifacts' JAIC 43(2) 151-160, 2004.

• Wikipedia: http://en.wikipedia.org/wiki/Supercritical_fluid (Accessed Dec. 9, 2005)

• Robert C. Reid The Properties of Gases and Liquids, McGraw-Hill, 1987.