SUPERCRITICAL FLUIDS
Supercritical fluids are highly compressed gases at temperatures and pressures above the critical point. They combine properties of gases and liquids in a very intriguing manner. Due to the high compressibility of supercritical fluids, small changes in pressure can produce substantial changes in density which, in turn, affect diffusivity, viscosity, dielectric, and solvation properties of these fluids, thus dramatically influencing the kinetics and mechanisms of chemical reactions.
For example:
Under supercritical conditions water is able to dissolve many nonpolar organic compounds, including PCBs. At high enough pressures it is miscible in all proportions with both organic compounds and oxygen. Thus, these compounds can be oxidized in a homogeneous supercritical phase, with the further removal of products from solution by either dropping the pressure or by cooling. This constitutes the essence of many promising new technologies. For instance, supercritical water oxidation(SCWO) processes can successully degrade dioxin, PCBs, benzene, DDT, urea, cyanide, and dozens of other toxic substances, including chemical-warfare agents and solid-rocket propellants. Such processes are fast, offer greater than 99.99% destruction efficiency and, because they are closed systems, can control emissions much better than traditional incinerators. Homogeneous catalysis in the supercritical phase also offers many technological and environmental benefits.
For example:
Under supercritical conditions water is able to dissolve many nonpolar organic compounds, including PCBs. At high enough pressures it is miscible in all proportions with both organic compounds and oxygen. Thus, these compounds can be oxidized in a homogeneous supercritical phase, with the further removal of products from solution by either dropping the pressure or by cooling. This constitutes the essence of many promising new technologies. For instance, supercritical water oxidation(SCWO) processes can successully degrade dioxin, PCBs, benzene, DDT, urea, cyanide, and dozens of other toxic substances, including chemical-warfare agents and solid-rocket propellants. Such processes are fast, offer greater than 99.99% destruction efficiency and, because they are closed systems, can control emissions much better than traditional incinerators. Homogeneous catalysis in the supercritical phase also offers many technological and environmental benefits.
Reference: Kalinichev, Andrew. (2014). Supercritical fluids and their technological applications. may 6th, 2015, from Subatech web: http://www.emn.fr/z-subatech/kalinich/scf.html