The document discusses various methods for making cotton dyeing more environmentally friendly. It focuses on reducing the amount of dyes, salts, and other chemicals released in effluents. Some key methods mentioned are using bifunctional reactive dyes for lower color effluents, low salt reactive dyes to reduce salt, replacing sodium hydrosulfite and sodium sulfide reducing agents, and dyeing at lower liquor ratios. The goal is to meet environmental standards while maintaining dye yield and fabric quality.

1. ENVIRONMENT FRIENDLY DYEING OF COTTON R.B.CHAVAN Department of Textile Technology Indian Institute of Technology Hauz-khas, New Delhi 110016 E-mail: rbchavan@hotmail.com

3. ENVIRONMENT FRIENDLY CHEMICAL PROCESSING Input / output analysis of Textile chemical Processes Textile Auxiliaries Dyes Base chemicals (e.g. acid, Alkali, sodium chloride) Textile Energy Natural Fibres; 10-20 MJ/kg Chemical Fibres: 5-50 MJ/kg Water 60-360 l/kg textile Polluted Air Water Effluent Waste Sewage sludge: 60-70 g/kg textile Wet Processing (pre-treatment, dyeing, printing, finishing.)

6. Typical dye fixation on different fibres

9. BIFUNCTIONAL REACTIVE DYES

13. GENERAL STRUCTURE OF LOW SALT REACTIVE DYES CHROMOPH-ORE CHROMOPHORE BRID-GE REACT-IVE GROUP REACT-IVE GROUP

14. ADVANTAGES OF HIGH DYE FIXATION Conventional dyes 60 % fixation Cibacron LS (bireactive) 80 % fixation 200 gm into the waste water 800 gm on the fibre 1 kg dye + 33% % - 50% % 1 kg dye 600 gm on the fibre 400 gm into the waste water