Eco friendly in textile processing

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  • 1.Eco Friendly In Textile WetProcessing By Aravin Prince Periyasamyaravinprince@gmail.com1

2. SupercriticalCarbon 2 3. What is supercritical carbondioxide? A supercritical fluid is a substance above itscritical temperature and critical pressure.Underthese conditions the distinctionbetween gases and liquids does not applyand the substance can only be described asa fluid. 3 4. Supercritical Fluid of CO2 4 5. Above 31.10C and 73 atm carbondioxide behaves as a supercritical fluidand shows properties of both a liquidand a gasIt fills the container, like a gas, anddissolves substances like a liquid. 5 6. Supercritical fluid of CO2 Withanincrease in temperature the meniscus begins to diminish. The liquid density falls due to expansion and the gas density rises as more of the substance evaporates.aravinprince@gmail.com6 7. Supercritical fluid of CO2 Oncethecriticaltemperature and pressurehave been reached the twodistinct phases of liquid andgas are no longer visible.The meniscus can no longerbe seen. One homogenousphasecalledthe"supercritical fluid" 7 8. Industrial extraction withsupercritical CO2 Decaffeinating coffee and tea Extracting bitterness to make beer Defatting cocoa powder Extracting spices and aromatic plants 8 9. Significant properties of supercritical fluidsDiffusivitygas > supercritical fluid > liquidViscositygas < supercritical fluid < liquidSurface tension gas = supercritical fluid < liquidDensitygas < supercritical fluid < or = liquidaravinprince@gmail.com9 10. Benefits of using supercritical CO2 for extraction It is having the penetration power of a gasand the extraction power of a liquid. It acts as a solvent to extract organiccompounds with a low molecular weight. It leaves no residual trace on treatedmaterial It respects the environment. 10 11. Supercritical CO2 as solvent Purification of specialty chemicals anduseful natural products An alternative solvent in coatings industry(replacing 40 - 90% of volatile solvents) Degreasing and dry cleaning applications Increasingly applied as a solvents insynthetic industrial processes 11 12. Use of supercritical CO2 in dyeing 12 13. Use of supercritical CO2 in dyeing 13 14. Enzymes 14 15. 15 16. Electron-ray treatment 16 17. MicrowavesMicrowaves are electromagnetic waves whosefrequency ranges from 1000MHz to10,00,000MHz.Microwave dyeing takes into account only thedielectric and the thermal properties.The dielectric property refers to the intrinsicelectrical properties that affect the dyeing bydipolar rotation of the dye and influences themicrowave field upon the dipoles. 17 18. The aqueous solution of dye has two componentswhich are polar, in the high frequency microwavefield oscillating at 2450MHz. It influences thevibrational energy in the water molecules and thedye molecules. Theheatingmechanism is through ionicconduction, which is a type of resistance heating.Depending on the acceleration of the ions throughthe dye solution, it results in collision of dyemolecules with the molecules of the fiber. This helps and affects the penetration of the dyeand also the depth to which the penetration takesplace in the fabric. This makes microwave superiorto conventional dyeing techniquesaravinprince@gmail.com18 19. Ultrasonic Treatments 19 20. Electrochemical dyeing Vat and sulphur dyeing involves both a reducing and an oxidising step, which are carried out with chemical oxidants and reducing agents. The environmental concerns associated with the use of these chemicals are many. An attractive alternative technique is to reduce and oxidise the dye by means of electrochemical methods.With direct electrolysis the dye itself is reduced at the surfaceof the cathode. In indirect electrolysis the reducing power ofthe cathode is transferred to the solution by a solublereversible redox system (e.g. based on antraquinone chemistryor iron complexes). With this reversible redox system thereducing agent is continuously regenerated at the cathode,which thus allows full recycling of the dye bath and thereducing agent. Direct cathodic reduction in an electrochemical cell is applicable to sulphur dyes. Vat dyes are reduced by indirect aravinprince@gmail.com20 electrolysis. 21. Plasma 21 22. 4th State of Matter PlasmaElectrically neutral +ve, -ve Charges, Radicals, Electrons, Excited molecules, atoms. Highly Reactive & Energetic 22 23. Sun Lightening boltHydrogen Bomb 23 24. Thermal PlasmaCold Plasma Hybrid PlasmaRT to Over 50, 24 25. Thermal PlasmaThermal Equilibrium Between Neutral Particles and the Charged Particles > 50,000c 25 26. PrinciplePotential Difference > Dielectric Strength13.56MHz RF Power 26 27. Gases UsedNon-polymerizing GasesHe, Ar, Air, Oxygen, Nitrogen, AndMixture Of GasesPolymerizing GasesCf4, 27 28. Major ApplicationsSynthetic Fibres/films Wettability Water Repellency Dyeability aravinprince@gmail.com28 29. ..Major Applications.Synthetic Fibres/filmsDeep Shades Soil Release Properties Composite Applications 29 30. ..Major Applications.Natural Fibres Shrinkage resistance Dyeability Fastness properties 30 31. 31