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- 2. TABLE OF CONTENT INTRODUCTION General information on supercritical fluids Supercritical fluid extraction Supercritical fluid chromatography Application conclusion 2
- 3. INTRODUCTION The use of supercritical fluids in various scientific and industrial applications has a rich and evolving history. From their discovery in the 19th century to their modern role in green chemistry, pharmaceuticals, and environmental science, the story of supercritical fluids is one of continuous innovation and expanding possibilities. 3
- 4. What is a supercritical fluid? Deffinition : supercritical fluid is any substance at a temperature and pressure above its critical point. Phase Diagram Example : Commonly used supercritical fluids are and . Critical point : represents the highest temperature and pressure at which the substance, can exist as a vapor and liquid in equilibrium. Fig 1: Phase diagram of Supercritical fluid, Region Characteristics of Supercritical fluids 4
- 5. Properties of SCF Combine propertise of a gases and liquids in a intrigning manner. Solvent power similar to light hydrocarbons for most of the solutes. Solubility increases with increasing density (that is with increasing pressure). The fluid are commonly miscible with permanent gases (e.g. N2, H2) and this leads to much higher concentration off dissolved gases, than can be archived in conventional solvents In general terms, supercritical fluid have properties, betweeen those of a gas and a liquid. 5
- 6. Common supercritical fluid: Carbon dioxide is commonly used due to : Environmentally freindly and generally recognized as safe by the food and dring administration (FDA). non toxique, non flammable, in expensive easy to remove from the product and its Tc and Pc are relatively low. Using CO2 as mobile phase even alow the extraction of thermally labile/ easily. Oxidisable compound even at low temperatures and non oxidant medium. 6
- 7. Critical properties of various solvents Solvent s Tc (K) Pc (MPa, atm) D(g/cm 3) 304.1 7.38 , 72.8 0.469 0 647.096 22.064, 217.755 0.322 190.4 4.60 , 45.4 0.162 305.3 4.87 , 48.1 0.203 369.8 4.25 (41.9) 0.217 282.4 5.04 (49.7) 0.215 364.9 4.60 (45.4) 0.232 512.6 8.09 (79.8) 0.272 513.9 6.14 (60.6) 0.276 508.1 4.70 (46.4) 0.278 7 Table 1. Critical properties of various solvents Table 2. Comparison of gases, supercritical fluids and liquids. Density (kg/m3 ) Viscosity ( µPa·s) Diffusivity (mm2 /s) Gases 1 10 1–10 Supercriti cal fluids 100–1000 50–100 0.01–0.1 Liquids 1000 500–1000 0.001
- 9. Supercritical fluid extraction (SFE) is eco-friendly alternative of extraction replacing organic solvents. In SFE use of supercritical fluids like supercritical as solvent is there. SCF helps in extraction of natural products of wide range of polarités. 9
- 10. Supercritical fluid extraction (SFE): continuous type : 10 1.CO is compressed and heated to a supercritical ₂ state. 2.The supercritical CO is then pumped through an ₂ extraction vessel containing the material to be extracted. The CO dissolves the desired compounds ₂ from the material, leaving behind the unwanted impurities. 3. The CO and extracted compounds are then passed ₂ through a pressure reduction valve. This causes the CO to expand and vaporize, leaving behind the ₂ extracted compounds. 4.The vaporized CO is then condensed and recycled ₂ for use in the next extraction cycle. 1 4 3 2
- 11. Advantage : Enhanced transport properties—solute diffuses more rapidly through a supercritical solvent than through a liquid solvent The solvent can be recovered as a gas by reducing the pressure, which offers the prospect of significant energy saving There is greater flexibility in the process operating parameters of pressure and temperature as compared with conventional liquid extraction processes. disadvantage : Its main disadvantages are the strong dependence on the matrix, mainly the particle size, on the extraction efficiency, and the high cost of both the equipment. The disadvantage of SCFE is that the capital cost of a SCFE plant is substantially higher (at least 50%) than a conventional extraction plant. 11
- 12. Supercritical fluid chromatography Supercritical fluid chromatography (SFC) is a separation technique that combines the principles of both gas chromatography (GC) and liquid chromatography (LC) with the use of supercritical fluids as the mobile phase. In SFC, carbon dioxide (CO2) is the most commonly employed supercritical fluid, along with a co-solvent, to perform chromatographic separations. 12
- 13. three main types of chromatography based in the nature of mobile phase: gas chromatography, liquid chromatography and super/subcritical chromatograph. 13
- 14. Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis. It can also be used for the separation of chiral compounds. SFC typically utilizes carbon dioxide as the mobile phase; therefore the entire chromatographic flow path must be pressurized. SFC is used in industry primarily for separation of chiral molecules, and uses the same columns as standard high performance liquid chromatography systems. 14
- 15. Fig 2: Schematic diagram of a supercritical fluid chromatograph designed for use with packed columns 15
- 16. Advantages and disadvantages of SFC: SFC is very clean; mobile phase contaminants are usually trace quantities of other gases. The mobile phase is free of dissolved oxygen and is not particularly reactive and the mobile phase is easily and rapidly removed. A disadvantage of using carbon dioxide as the mobile phase is it does not elute very polar or ionic compounds; this is overcome by using an organic modifier. However, there are some disadvantages of SFC these include that if molecules are highly polar they are not soluble in the mobile phase. Usually SFC only moves a small amount of a large specimen onto the column and has Limited availability. 16
- 17. Application: Decaffeination: Methods for decaffeinating coffee have been available since the early 20th Century. The aim is to remove caffeine without removing the compounds that give the coffee its flavour, and without leaving a toxic residue in the beans Several different solvents have been used: Table 3: Types of solvents for decaffeination 17
- 18. Fig 3: Decaffeination using supercritical carbon dioxide 18
- 19. conclusion In conclusion, supercritical fluid technology represents a remarkable and versatile tool in various scientific disciplines and industries. Its ability to efficiently separate and analyze complex mixtures, particularly in the fields of pharmaceuticals, natural product research, environmental monitoring, and more, has revolutionized the way we approach chromatography. By harnessing the unique properties of supercritical fluids, we can achieve faster, more selective, and environmentally friendly separations. 19