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Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
Innovations in dyeing of cotton with indigo
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Innovations in dyeing of cotton with indigo

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  • 1. INNOVATIONS IN DYEING OF COTTON WITH INDIGO R.B.CHAVAN, S.JAHAN, J.N.CHAKRABORTY Department of Textile Technology Indian Institute of Technology Hauz-Khas, New Delhi 110016
  • 2. FUNDAMENTALS <ul><li>SOLUBILIZED IN PRESENCE OF NaOH AND Na 2 S 2 O 4 </li></ul><ul><li>VERY LOW AFFINITY INDIGO </li></ul><ul><li>OLDEST NATURAL DYE, BELOGNS TO VAT DYE CLASS </li></ul><ul><li>SUNTHETIC INDIGO COMMERCIALLY MANUFACTURED IN 1897 </li></ul><ul><li>PRESENTLY MAJOR INDIGO PRODUCTION USED FOR DYEING OF DENIM </li></ul><ul><li>PROPERTIES </li></ul><ul><li>WATER INSOLUBLE </li></ul><ul><li>APPLICATION TROUGH MULTIPLE DIPS AND NIPS WITH INTERDEDIATE AIR OXIDATION </li></ul>
  • 3. pH EFFECT <ul><li>FIG </li></ul>
  • 4. TWO INDIGO FORMS <ul><li>MONO-PHENOLATE HAS HIGH AFFINITY THAN BI-PHENOLATE FORM </li></ul><ul><li>ADVANTAGES </li></ul><ul><li>TECHNICAL </li></ul><ul><li>LESS – VE CHARGE ON FIBRE, LESS DYE REPULSION </li></ul><ul><li>HIGH STRIKE RATE </li></ul><ul><li>RING DYEING </li></ul><ul><li>BETTER WASH DOWN EFFECTS </li></ul><ul><li>ENVIRONMENTAL </li></ul><ul><li>BETTER COLOUR YIELD </li></ul><ul><li>LESS DYE IN EFFLUENT </li></ul><ul><li>LOW EFFLUENT LOAD </li></ul><ul><li>SAVING IN DYE CONSUMPTION </li></ul><ul><li>LOW DYEING COST </li></ul>
  • 5. MATERIALS <ul><li>COMMERCIAL SYNTHETIC INDIGO </li></ul><ul><li>ALKALI </li></ul><ul><li>NaOH </li></ul><ul><li>ORGANIC ALKALIES – I, II, III, IV </li></ul><ul><li>(ALIPHATIC AMINES) </li></ul><ul><li>SODIUM HYDROSULPHITE </li></ul><ul><li>COTTON FABRIC </li></ul>
  • 6. EXPERIMENTAL <ul><li>INDIGO REDUCTION </li></ul><ul><li>STOCK VAT </li></ul><ul><li>INDIGO 2 gm </li></ul><ul><li>ALKALI X gm* </li></ul><ul><li>Na 2 S 2 O 4 1.5 gm </li></ul><ul><li>WATER 100 ml </li></ul><ul><li>VATTING AT ROOM TEMP., 10 MIN. </li></ul><ul><li>DILUTED TO 657 ml WITH DILUTION LIQUOR </li></ul><ul><li>*ALKAI </li></ul><ul><li>NaOH 1 gm </li></ul><ul><li>ORGANIC ALKAI I 2.43 gm </li></ul><ul><li>ORGANIC ALKALI II 3.81 gm </li></ul><ul><li>ORGANIC ALKALI II 2.24 gm </li></ul><ul><li>ORGANIC ALKALI IV 2.94 gm </li></ul>
  • 7. DYE BATH <ul><li>DILUTION LIQUOR </li></ul><ul><li>ALKALI x g/l* </li></ul><ul><li>Na 2 S 2 O 4 1.5 g/l </li></ul><ul><li>*NaOH 1.35 g/l </li></ul><ul><li>ORGANIC ALKALI AS PER NaOH EQUIVALENCE </li></ul><ul><li>PAD BATH </li></ul><ul><li>INDIGO 3 g/l </li></ul><ul><li>Na 2 S 2 O 4 3.55 g/l </li></ul><ul><li>ALKALI x g/l* </li></ul><ul><li>*NaOH 2.67 g/l </li></ul><ul><li>ORGANIC ALKALI AS PER NaOH EQUIVALENCE </li></ul>
  • 8. DYEING <ul><li>COTTON FABRIC PADDING WITH INDIGO SOLUTION (3 g/l), ROOM TEMPERATURE </li></ul><ul><li>DIPPING TIME 30 sec </li></ul><ul><li>AIR OXIDATION 60 sec </li></ul><ul><li>EXPRESSION 80% </li></ul><ul><li>6 DIP – 6 NIP </li></ul><ul><li>WASHING </li></ul><ul><li>SEVERAL COLD WATER RINSING </li></ul><ul><li>SOAP 2 g/l LISSAPOL D , 60 0 C, 10 min. </li></ul><ul><li>COLD WATER RINSE </li></ul>
  • 9. INDIGO ON FABRIC <ul><li>COLOUR DEPTH </li></ul><ul><li>K/S DETERMINATION AT 640 nm WAVELENGTH </li></ul><ul><li>%YIELD </li></ul><ul><li>K/S (NaOH) AS 100% </li></ul>
  • 10. NaOH EQUIVALENCE OF ORGANIC ALKALI <ul><li>TITRATION WITH 0.1N H 2 SO 4 </li></ul><ul><li>PHENOPHTHALEIN INDICATOR </li></ul><ul><li>RESULTS IN TERMS OF gm OF ORGANIC ALKALI EQUIVALENT TO 1 gm NaOH </li></ul>
  • 11. ALKALI CONCENTRATION IN DYE BATH <ul><li>10 ml DYE LIQUOR, </li></ul><ul><li>TITRATE WITH 0.1 N H 2 SO 4 UNTIL THE DROP OF DYE LIQUOR PLACED ON PHELOLPHTHALEIN PAPER DOES NOT SHOW RED COLOUR </li></ul>
  • 12. NA 2 S 2 O 4 CONCENTRATION IN DYEBATH <ul><li>10 ml DYE LIQUOR </li></ul><ul><li>ADD </li></ul><ul><li>1 ml FORMALDEHYDE, 5 ml ACETIC ACID </li></ul><ul><li>TITRATE: 0.1 n IODINE SOLUTION </li></ul><ul><li>SPOT TITRATED LIQUOR ON STARCH PAPER </li></ul><ul><li>CONTINUE TITRATION TILL </li></ul><ul><li>LIQUOR DROP PRODUCE DARK BLUE (Black) SPOT SURROUNDED BY VIOLET RING </li></ul><ul><li>DETERMINE Na 2 S 2 O 4 FROM IODINE CONSUMED </li></ul>
  • 13. NaOH Equivalence of Organic Alkalis 2.43 3.81 2.24 2.94 Organic Alkali I Organic Alkali II Organic Alkali III Organic Alkali IV NaOH Equivalence (1gm) Organic Alkali
  • 14. DYEBATH STABILITY AND COLOUR BUILD UP <ul><li>DURING DYEING THERE IS CONSUMPTION OF Na 2 S 2 O 4 AND ALKALI </li></ul><ul><li>ORGANIC ALKLIS BEING WEAK, THERE IS POSSIBILITY OF THEIR RAPID CONSUMPTION AFFECTING DYE-BATH STABILITY AND COLOUR YIELD </li></ul><ul><li>DYE-BATH STABILITY AND COLOUR YIELD WERE TESTED BY CARRYING OUT DYEING (6DIP-6 NIP) AFTER STORAGE OF LEUCO VAT FOR DIFFERENT INTERVALS OF TIME. </li></ul>
  • 15. Effect of Different Alkalis on Indigo Dye bath Stability and Colour Build up 100/15 110.0 63.5 104.6 124.4 100/14 121.1 - 137.5 155.8 100/14 118.6 148.5 140.1 146.1 100/13 133 155 133.6 143.1 100/13 128 142 131 139 NaOH Organic Alkali I Organic Alkali II Organic Alkali III Organic Alkali IV 8hrs 6hrs 4hrs 2hrs 0hrs Alkali
  • 16. OBSERVATIONS <ul><li>ALL ORGANIC ALKALIS SHOWED HIGHER COLOUR YIELD THAN NaOH </li></ul><ul><li>ALL LEUCO INDIGO SOLUTIONS WERE STABLE EXCEPT ORGANIC ALKALI II </li></ul><ul><li>AFTER 24 hrs. NO ALKALI INCLUDING NaOH WAS ABLE TO MAINTAIN INDIGO IN LEUCO FORM </li></ul><ul><li>THE HIGHER COLUR YIELD IN CASE OF ORGANIC ALKALI MAY BE RELATED TO pH OF INDIGO BATH </li></ul>
  • 17. CHANGE OF pH WITH TIME BEFORE PADDING 11.4 10.3 9.6 10.1 10.2 11.4 10.5 10.0 10.4 10.5 11.5 10.6 10.3 10.5 10.5 11.6 10.7 10.5 10.7 10.6 12.3 10.8 10.6 10.8 10.8 NaOH Organic Alkali I Organic Alkali II Organic Alkali III Organic Alkali IV 8hr 6hr 4hr 2hr 0hr Alkali
  • 18. OBSERVATIONS <ul><li>NaOH STRONGER ALKAI SHOWED pH 12.3 </li></ul><ul><li>ORGANIC ALKALIS SHOWED pH 10.8 </li></ul><ul><li>ACCORDING TO LITERATURE </li></ul><ul><li>INDIGO SHOWS MAX. COLOUR YIELD AT pH 10.5-11.5 </li></ul><ul><li>INDIGO IN MONO-PHENOLATE FORM </li></ul><ul><li>HIGH AFFINITY TO COTTON </li></ul><ul><li>BETTER COLOUR YIELD COMPARED TO NaOH </li></ul><ul><li>IN CASE OF NaOH, INDIGO IN BI-PHENOLATE FORM </li></ul><ul><li>LOW AFFINITY </li></ul>
  • 19. Effect of Number of dips on Alkali Consumption 17.5 15.8 14.8 29.9 16.2 14.3 12.2 28.1 15.0 13.1 9.5 20.5 12.5 11.8 8.7 21.8 11.2 9.2 7.8 18.7 10 7.9 6.9 12.5 NaOH Organic Alkali I Organic Alkali III Organic Alkali IV 6 5 4 3 2 1 % Consumption of alkali after each dip Alkali
  • 20. ALKALI CONSUMPTION <ul><li>NEUTRALIZATION BY NaHSO 3 FORMED BY OXIDATION OF Na 2 S 2 O 4 </li></ul><ul><li>NEUTRALIZATION BY ATMOSPHERIC CO 2 </li></ul><ul><li>ADSORPTION BY COTTON </li></ul><ul><li>ALKALI CONSUMPTION TO AN EXTENT OF 15-17% EXCEPT ORGANIC ALKALI IV (30%) </li></ul>
  • 21. Effect of Number of dips on Na 2 S 2 O 4 Consumption 89.2 89.0 81.7 83.0 78.5 80.8 79.8 76.7 67.8 80.0 73.1 67.8 60.7 74.5 67.3 58.9 53.5 67.2 61.5 53.6 48.2 52.0 40.3 37.5 NaOH Organic Alkali I Organic Alkali III Organic Alkali IV 6 5 4 3 2 1 % Consumption of Na 2 S 2 O 4 Alkali
  • 22. Na 2 S 2 O 4 CONSUMPTION <ul><li>OXIDATION DUE TO ATMOSPHERIC OXYGEN </li></ul><ul><li>CONSUMPTION DURING 1 st DIP IS HIGH </li></ul><ul><li>INTRODUCTION OF OCCLUDED AIR BY COTTON </li></ul><ul><li>AT THE END OF 6 DIPS Na 2 S 2 O 4 CONSUMPTION IS 80-90% </li></ul><ul><li>HIGH Na 2 S 2 O 4 CONSUMPTION IS THE MAIN CAUSE FOR DYE BATH INSTABILITY </li></ul>
  • 23. SIMULATION OF COMMERCIAL DYEING PRACTICE <ul><li>RESIDUAL DYE-BATH USED SEVERAL TIMES IN COMMERCIAL PRACTICE AFTER REPLENISHING WITH ALKALI AND Na 2 S 2 O 4 </li></ul><ul><li>THE DYEINGS OF 1 st DAY AND 7 th DAY ARE ALMOST IDENTICAL </li></ul>
  • 24. SIMULATION OF COMMERCIAL DYEING PRACTICE 11.9 10.7 16.3 19.7 12.3 10.9 16.7 20.7 NaOH Organic Alkali I pH K/S pH K/S Sample of the 7 th day Sample of the 1 st day Alkali
  • 25. CONCLUSION <ul><li>ORGANIC ALKALIS SHOWED HIGHER COLOUR YIELD OF INDIGO COMPARED TO NaOH </li></ul><ul><li>IN PRESENCE OF ORGANIC ALKALI, LEUCO INDIGO IS IN MONO-PHENOLATE FORM </li></ul><ul><li>NaOH MAY BE SUBSTITUTED BY ORGANIC ALKALI. </li></ul><ul><li>ESSENTIAL TO ESTABLISH ON THE BASIS OF BULK SCALE TRIALS AND COSTING </li></ul>
  • 26. IRON (II) SALT COMPLEXES <ul><li>PROBLEMS WITH Na 2 S 2 O 4 </li></ul><ul><li>DECOPOSE OXIDATIVELY AND THERMALLY TO SEVERAL BY-PRODUCTS </li></ul><ul><li>ONLY A PORTION IS AVAILABLE FOR DYE REDUCTION </li></ul><ul><li>SOME BY-PRODUCTS ARE ACIDIC </li></ul><ul><li>ABOUT 3 TIMES MORE NaOH AND Na 2 S 2 O 4 OVER STOICHOMETRIC REQUIREMENT </li></ul><ul><li>BY-PRODUCTS </li></ul><ul><li>Na 2 S AND NaHS: POLLUTE ATMOSPHERE, FORMATION OF H 2 S </li></ul><ul><li>Na2SO3, NaHSO4, Na2SO4, Na2S2O3: CONTAMINATE SEWAGE, CORRODE CEMENT PIPES </li></ul>
  • 27. ALTERNATIVE ECO-FRIENDLY REDUCING AGENTS <ul><li>ELECTROCHEMICAL REDUCTION </li></ul><ul><li>HYDROXY ACETONE </li></ul><ul><li>IRON PENTACARBONYL COMPOUNDS </li></ul><ul><li>IRON (II) SALT COMPLEXES </li></ul>
  • 28. IRON (II) SALT COMPLEXES <ul><li>FeSO 4 AND Ca(OH) 2 OLDEST METHOD </li></ul><ul><li>BULKY SEDIMENTS, POOR SOLUBILITY OF Fe(OH) 2 </li></ul><ul><li>NON-REPRODUCIBLE RSULTS </li></ul><ul><li>MODERN APPROACH </li></ul><ul><li>SLUBILIZATION OF Fe(OH)2 THROUGH COMPLEX FORMATION </li></ul><ul><li>GLUCONIC ACID AS LIGAND HAS BEEN INVESTIGATED IN GERMAN LITERATURE (1995) </li></ul>
  • 29. Fe(OH) 2 AS REDUCING AGENT

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