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Super critical fluid
Supercritical fluid extraction uses supercritical fluids like carbon dioxide above their critical temperature and pressure to extract compounds. This allows extraction to occur quickly in 10-60 minutes without solvent residues. Carbon dioxide is commonly used as it is non-toxic, inexpensive, and allows extraction of thermally sensitive compounds at low temperatures. The supercritical fluid is pumped to the extraction vessel containing the sample, where compounds dissolve and are then collected by reducing the pressure and separating the compounds. This technique is used to extract compounds for food, cosmetics, and pharmaceuticals and to remove alcohol from beverages.
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Super critical fluid
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- 2. abstract Supercritical fluid extractionis the most effective and efficient way to extract valuable constituent botanicals. Supercritical Fluid Extraction (SFE) is the process of separating one component (the extractant) from another (the matrix) using supercritical fluids that is CO2 as the extracting solvent. CO2 is the king of extraction solvents for botanicals. Extraction conditions for supercritical CO2 are above the critical temperature of 31°C and critical pressure of 74 bar. Supercritical fluids are highly compressed gases, which have combined properties of gases and liquids in an intriguing manner. Supercritical fluids can lead to reactions, which are difficult or even impossible to achieve in conventional solvents. It is a fast process completed in 10 to 60 minutes. A supercritical fluid can be separated from analyte by simply releasing pressure, leaving almost no trace and yields a pure residue. Key words: Supercritical fluid extraction, Applications.
- 3. INTRODUCTION extraction process? Extractioncan be defined as the removal of soluble material from an insoluble residue, either liquid or solid, by treatment with a liquid solvent. It is therefore, a solution process and depends on the mass transfer phenomena. The controlling factor in the rate of extraction is normally the rate of diffusion of the solute by the liquid boundary layer at the interface.
- 4. OBJECTIVES • Introduction toSCFE • Common SCF and their common properties • Instrumentation of SCF extraction • Advantages and application of SCFE
- 5. Super Critical FluidExtraction Extraction of compounds of interest using super critical fluid as an extracting solvent/mobile phase. Resembles soxhlet extraction except the fact that the solvent used here is SCF. The SCF state occur when a fluid is above its critical temperature and critical pressure i.e. between the typical gas and liquid state. During which the solvating power of mobile phase will be at its peak. The first reported observation was made by Baron in 1822. In 1970 significant development in the field off SCFE occurred by decaffeination of green coffee with CO2 as SCF.
- 6. Supercritical fluid Asupercritical fluid is any substance at a temperature and pressure above its critical point. It can diffuse through solids like a gas, and dissolve materials like a liquid. It exhibit physicochemical properties intermediate between those of liquid and gases. Small changes in pressure and temperature results in greater changes in density allowing many properties of SCF to be fine tuned thus SCF can preferably substitute organic solvents for many of the industrial and laboratory processes.
- 7. Phase diagram ofSCF Critical temperature(TC): highest temp at which a gas can be converted to a liquid by increase in pressure. Critical pressure (PC): highest pressure at which a liquid can be converted to a gas by increase in temperature. Triple point (TP): a point at which gas liquid and solid phases exist in equilibrium.
- 8. Common SCF Among therange of super critical fluids used water is used for power generation and CO2 for decaffeination. Carbon dioxide is Environmentally friendly and generally recognized as safe by the food and drug administration (FDA) Odorless, non-toxic, non-flammable, inexpensive, easy to remove from the product and its TC and PC are relatively low. Using CO2 as mobile phase even allow the extraction of thermally labile/easily oxidisable compounds even at low temperatures and non oxidant medium.
- 9. Properties of supercriticalfluid combine properties of gases and liquids in an intriguing manner. solvent power similar to light hydrocarbons for most of the solutes. Solubility increases with increasing density (that is with increasing pressure). The fluids are commonly miscible with permanent gases (e.g. N2 or H2) and this leads to much higher concentrations of dissolved gases than can be achieved in conventional solvents. In general terms, supercritical fluids have properties between those of a gas and a liquid.
- 10. Critical properties forsome components commonly used as supercritical fluids
- 11. Extraction process bySCF The system must contain a pump for the CO2, a pressure cell to contain the sample, The liquid is pumped to a heating zone, where it is heated to supercritical conditions. It then passes into the extraction vessel, where it rapidly diffuses into the solid matrix and dissolves the material to be extracted. The dissolved material is swept from the extraction cell into a separator at lower pressure, and the extracted material settles out. The CO2 can then be cooled, recompressed and recycled, or discharged to atmosphere.
- 12. Flow diagram ofworking.
- 13. Two mode torun the instrument Static extraction The mobile phase fills the extraction cell and interacts with the sample. The second pump is opened and the extracted surface are taken out at once. Dynamic extraction The second pump sending the material out to the collection chamber is always open during the extraction process thus the mobile phase reaches the extraction cell and extracts components in order to take them out consistently.
- 14. Pump Carbon dioxideis usually pumped as a liquid, usually below 5°C and a pressure of about 50 bars. The solvent is pumped as a liquid as it is then almost incompressible. For small-scale extractions (up to a few grams/minute), reciprocating CO2 pumps or syringe pumps are often used. For larger scale extractions, diaphragm pumps are most common.
- 15. Pressure vessels Pressurevessels can range from simple tubing to more sophisticated purpose built vessels with quick release fittings. The pressure requirement is at least 74 bars, The vessel must be equipped with a means of heating. Care must be taken if rubber seals are used on the vessel, as the CO2 may dissolve in the rubber, causing swelling, and the rubber will rupture on depressurization.
- 16. Collection The supercriticalsolvent is passed into a vessel at lower pressure than the extraction vessel. The density, and thus, dissolving power, of supercritical fluids varies sharply with pressure, and hence, the solubility in the lower density CO2 is much lower, and the material precipitates for collection. It is possible to fractionate the dissolved material using a series of vessels at reducing pressure.
- 17. Heating and cooling The fluid is cooled before pumping to maintain liquid conditions, and then heated after pressurization. As the fluid is expanded into the separator, heat must be provided to prevent excessive cooling
- 18. Application of SCFextraction- Separation of essential and its derivative for use in food, cosmetics and pharmaceutical industry. Extraction of oil is used to produce fat free potato chips and snack food to satisfy the consumer need for lighter food. Separation of tocopherol and other anti oxidant because they have greater solubility in CO2 Removal of alcohol from wine, beer and similar products. Supercritical CO2 coupled with HPLC to extract and characterize antimicrobial compounds and food preservatives. Used to determine the fat content of numerous food products ranging from beef to oil seeds and vegetables. Application in food safety: used in food pollutants analysis, mainly pesticide residue and environmental pollutants. Etc.