Supercritical Fluids for this Super Critical Time

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Supercritical Fluids for this Super Critical Time

  1. 1. A SUPERCRITICAL FLUID FOR THIS SUPER CRITICAL TIME<br />HeeJia Min<br />Melissa Yeo<br />Jasmine Tan<br />Zou Yuhan<br />Nanyang Girls’ High School<br />
  2. 2. What is our world like in 2111?<br />
  3. 3. Pollution!<br />Cause: <br /> Disposal of industrial waste into water bodies/air<br />
  4. 4. Pollution!<br />What we need:<br />Environmentally benign manufacturing methodology<br />Reduced waste production<br />
  5. 5. Global Warming<br />Cause:<br /> CO2 emissions from industries<br />
  6. 6. Global Warming!<br />What we need:<br /> To recover & reuse (not release) CO2<br />
  7. 7. Energy Shortage!<br />What we need:<br />Energy-efficient manufacturing processes<br />
  8. 8. Our Future… 2111<br />
  9. 9. Introducing Supercritical Fluids… <br />
  10. 10.
  11. 11. ?<br />SUPERCRITICAL FLUID<br />
  12. 12.
  13. 13. Critical Temperature<br />The highest temperature at which a gas can be converted to a liquid by an increase in pressure<br />
  14. 14. Critical Pressure<br />The highest pressure at which a liquid can be converted to a gas by an increase in temperature<br />
  15. 15. Supercritical Fluid<br />
  16. 16. How are supercritical fluids formed?<br />Particles are compressed by high pressure<br />Not gas<br />Particles have a large amount of kinetic energy (due to high temperature)<br />Not liquid<br />Have properties intermediate between those of gases and liquids<br />
  17. 17. How are supercritical fluids formed?<br />Separate phases of CO2 Meniscus is easily observed<br />
  18. 18. How are supercritical fluids formed?<br />Increased temp; meniscus begins to diminish<br />
  19. 19. How are supercritical fluids formed?<br />Gas and liquid densities to become more similar<br />
  20. 20. How are supercritical fluids formed?<br />Meniscus no longer seen; One homogenous phase phase occurs<br />
  21. 21. What are the properties of supercritical fluids?<br />
  22. 22. Solvating Power<br />Solvating power: ability of a solvent to dissolve a solute<br />Good solvent<br /> - Near liquid density <br />
  23. 23. Diffusivity<br />High diffusivity<br />Due to its gas-like properties<br />Lower density than liquid: more space for particles to move<br />High temperatures: particles move faster<br />
  24. 24. Diffusivity<br />
  25. 25. Viscosity<br /><ul><li>10-100 times lower than liquids
  26. 26. Particles are far apart</li></li></ul><li>Surface Tension<br />No surface tension <br />There is no liquid/gas phase boundary)<br />
  27. 27. Environmental Friendliness<br />Replaces harmful organic based solvents <br />e.g. chloroform<br />Has persistent organic pollutants<br />
  28. 28. Polarity<br />Most supercritical fluids behave like non-polar solvents<br />Possible to tune their polarity by adding a polar co-solvent <br />e.g. ethanol <br />Increases the solubility for specific compounds<br />
  29. 29. Advantages of SCFs<br />Combination of useful properties of liquids & gases<br />Good solvents<br />Penetrate materials easily<br />Can be altered by varying pressure and temperature<br /><ul><li>Solvent of solutes with different solubilities
  30. 30. Antisolvent</li></li></ul><li>FOCUS: Carbon Dioxide Supercritical Fluid<br />
  31. 31. Why Carbon Dioxide?<br />Low critical temperature (31°C)<br />Safe to use<br />Non-toxic<br />Non-flammable<br />Chemically inert<br />
  32. 32. Why Carbon Dioxide?<br />Inorganic<br />No residual VOCs<br />Reusable<br />Supercritical CO2 as a solvent can be recovered and recycled<br />Odourless<br />No unpleasant odours<br />
  33. 33. Supercritical Fluid Processes<br />
  34. 34. Extraction<br />
  35. 35. Extraction<br />Advantage :<br />Efficient isolation of components <br />
  36. 36. Extraction<br />
  37. 37. Fluoropolymer Production<br />Problems with present dispersion mediums:<br />Using water: Low product quality<br />Using organic compounds: Severe environmental hazards<br />
  38. 38. Fluoropolymer Production<br />Advantages of using supercritical CO2 :<br />Products easily isolated and dried<br />Minimal waste<br />
  39. 39. Cleaning<br />Process is similar to extraction – Substances “extracted” are impurities, etc <br />Applications:<br />Precision cleaning<br />Dry cleaning<br />Preserving artworks<br />
  40. 40. Formation of nanoparticles<br />Rapid Expansion of Supercritical Solutions (RESS)<br />Sudden pressure drop<br />Dissolved material precipitated out<br />Crystals formed enclose a small amount of the supercritcal solvent<br />Supercritical fluid changes to its normal state (usually gas)<br />Crystal broken from inside-out<br />Forms nanoparticles<br />
  41. 41. Formation of nanoparticles<br />Advantages of<br /> using supercritical fluid<br />Easy isolation<br />Particles formed are shown to be extremely homogeneous in size<br />Short processing times<br />
  42. 42. Drying<br />Normal Drying (follow green arrow)<br />Problems:<br />Surface tension in the liquid body pulls against solid structures<br />Breaks delicate structures<br />
  43. 43. Drying<br />Supercritical drying (red arrow):<br />No surface tension<br /><ul><li>Applications
  44. 44. Drying of spices
  45. 45. Production of aerogel </li></li></ul><li>How does the future of supercritical fluid technology look like?<br />
  46. 46. Manufacturing<br />Incorporation of aforementioned processes <br />Better alternative to traditional solvents<br />Sustainable way to meet rising needs of growing population<br />
  47. 47. Medicine<br />Preparation and coating of drugs<br />Formation of powders of macromolecules<br />Microporous Foams for tissue engineering <br />Sterilisation<br />
  48. 48. Geothermal Energy Generation<br />Current system:<br />Water is pumped deep underground to collect heat<br />Supercritical CO2 to replace water<br />Flows more freely through rock<br />Eliminates need to pump fluid<br />CO2 sequestration<br />
  49. 49. Recycling Radioactive Wastes<br />Used to recover uranium from ashes of radioactive garbage<br />Nearly 10% of radioactive ash weight<br />Worth about $900 per pound<br />
  50. 50. Space Exploration<br /><ul><li>Supercritical carbon dioxide extraction allows astronauts to exploit elements on Mars:
  51. 51. Magnesium and hydrogen for rocket fuel
  52. 52. Oxygen to breathe
  53. 53. Water to drink
  54. 54. The Martian atmosphere provides in-situ source of carbon dioxide</li></li></ul><li>Conclusion<br />Main reason for current limited use:<br />Lack of awareness of benefits of technology, as well as experienced user knowledge<br />Solution: Further research and more widespread use<br />
  55. 55. Conclusion<br />High initial start-up costs associated with developing task-specific equipment<br />Solutions:<br />Further research to develop technology<br />Prohibition of certain traditional solvents that although are cheaper (in the short-term), are detrimental to our environment/human health<br />Cost/benefit analysis of the technology<br />
  56. 56. THANK YOU!<br />

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