1. A SUPERCRITICAL FLUID FOR THIS SUPER CRITICAL TIME HeeJia Min Melissa Yeo Jasmine Tan Zou Yuhan Nanyang Girls’ High School

2. What is our world like in 2111?

3. Pollution! Cause: Disposal of industrial waste into water bodies/air

4. Pollution! What we need: Environmentally benign manufacturing methodology Reduced waste production

5. Global Warming Cause: CO2 emissions from industries

6. Global Warming! What we need: To recover & reuse (not release) CO2

7. Energy Shortage! What we need: Energy-efficient manufacturing processes

8. Our Future… 2111

9. Introducing Supercritical Fluids…

11. ? SUPERCRITICAL FLUID

13. Critical Temperature The highest temperature at which a gas can be converted to a liquid by an increase in pressure

14. Critical Pressure The highest pressure at which a liquid can be converted to a gas by an increase in temperature

15. Supercritical Fluid

16. How are supercritical fluids formed? Particles are compressed by high pressure Not gas Particles have a large amount of kinetic energy (due to high temperature) Not liquid Have properties intermediate between those of gases and liquids

17. How are supercritical fluids formed? Separate phases of CO2 Meniscus is easily observed

18. How are supercritical fluids formed? Increased temp; meniscus begins to diminish

19. How are supercritical fluids formed? Gas and liquid densities to become more similar

20. How are supercritical fluids formed? Meniscus no longer seen; One homogenous phase phase occurs

21. What are the properties of supercritical fluids?

22. Solvating Power Solvating power: ability of a solvent to dissolve a solute Good solvent - Near liquid density

23. Diffusivity High diffusivity Due to its gas-like properties Lower density than liquid: more space for particles to move High temperatures: particles move faster

24. Diffusivity

27. Environmental Friendliness Replaces harmful organic based solvents e.g. chloroform Has persistent organic pollutants

28. Polarity Most supercritical fluids behave like non-polar solvents Possible to tune their polarity by adding a polar co-solvent e.g. ethanol Increases the solubility for specific compounds

31. Why Carbon Dioxide? Low critical temperature (31°C) Safe to use Non-toxic Non-flammable Chemically inert

32. Why Carbon Dioxide? Inorganic No residual VOCs Reusable Supercritical CO2 as a solvent can be recovered and recycled Odourless No unpleasant odours

33. Supercritical Fluid Processes

34. Extraction

35. Extraction Advantage : Efficient isolation of components

36. Extraction

37. Fluoropolymer Production Problems with present dispersion mediums: Using water: Low product quality Using organic compounds: Severe environmental hazards

38. Fluoropolymer Production Advantages of using supercritical CO2 : Products easily isolated and dried Minimal waste

39. Cleaning Process is similar to extraction – Substances “extracted” are impurities, etc Applications: Precision cleaning Dry cleaning Preserving artworks

40. Formation of nanoparticles Rapid Expansion of Supercritical Solutions (RESS) Sudden pressure drop Dissolved material precipitated out Crystals formed enclose a small amount of the supercritcal solvent Supercritical fluid changes to its normal state (usually gas) Crystal broken from inside-out Forms nanoparticles

41. Formation of nanoparticles Advantages of using supercritical fluid Easy isolation Particles formed are shown to be extremely homogeneous in size Short processing times

42. Drying Normal Drying (follow green arrow) Problems: Surface tension in the liquid body pulls against solid structures Breaks delicate structures

44. Drying of spices

46. Manufacturing Incorporation of aforementioned processes Better alternative to traditional solvents Sustainable way to meet rising needs of growing population

47. Medicine Preparation and coating of drugs Formation of powders of macromolecules Microporous Foams for tissue engineering Sterilisation

48. Geothermal Energy Generation Current system: Water is pumped deep underground to collect heat Supercritical CO2 to replace water Flows more freely through rock Eliminates need to pump fluid CO2 sequestration

49. Recycling Radioactive Wastes Used to recover uranium from ashes of radioactive garbage Nearly 10% of radioactive ash weight Worth about $900 per pound

51. Magnesium and hydrogen for rocket fuel

52. Oxygen to breathe

53. Water to drink

55. Conclusion High initial start-up costs associated with developing task-specific equipment Solutions: Further research to develop technology Prohibition of certain traditional solvents that although are cheaper (in the short-term), are detrimental to our environment/human health Cost/benefit analysis of the technology

56. THANK YOU!