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Extractions' breakthrough. . .
Most industrial-scale separation processes employ energy-intensive methods, such as distillation. The chemical and petroleum industries consume 5.8 quads of energy per year. Distillation accounts for 95% of all separation processes consuming 2.52 quads of energy annually, which makes it imperative to seek innovative, energy-saving and environmentally benign separation techniques such as Supercritical CO2 Technology.
When carbon dioxide is below the critical parameters, (Pc=73.8 atm and Tc=31.1o C) two distinct phases exist, liquid and vapor. By increasing the system temperature, the liquid expands and the two phases become less distinct forming a new phase, which is known as the Supercritical State. This Supercritical State has very powerful solvent properties of gas compressed to its critical point, defined by the pressure and temperature. A Supercritical State has a useful combination of liquid-like density and solvency, and gas-like viscosity, diffusivity, compressibility and lack of surface tension. Therefore, CO2 rapidly penetrates substrates and dissolves a wide range of chemicals. This critical region of CO2 is characterized by an ability to control the solvent power with only minor changes in pressure and temperature, resulting in more extracts selectivity. A reverse process occurs by decreasing the system temperature resulting in a phase separation between the liquid and the vapor.
CO2 is the most often investigated and used supercritical fluid because it is environmentally benign, energy-efficient and provides cost-efficient processes.
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Some additional advantages of CO2 are:
- Neither carcinogenic nor corrosive to human tissues
- A naturally occurring fluid that is chemically inert and physiologically compatible
- Not flammable, does not explode and is extremely stable
- A safer alternative to many of the chemicals traditionally used for separation processes
- Relatively inexpensive and very economical, over 90% can be recovered and reused in our processes
- Energy conservative because it has a lower evaporation temperature than most organic solvents
- A solvent with higher diffusion coefficients, which leads to higher extraction and reaction rates
- A gentle solvent for treatment of temperature-sensitive natural substances, which can be separated with high purity while retaining aroma
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