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Tuesday, March 12, 2013

Sulphur Black Dyeing - The problem & Solution

Black colour on garments, jeans etc have a special place among the Youth and others too...sulphure black dyeing is generally used to impart black colours..
  • Sulfur dyes are water insoluble compounds that have to be converted during the dyeing process first into a water-soluble form and then to a reduced form to enable fixing of the dye on the fiber to be dyed
  • Converting the original dye into water solubility is by treatment with an aqueous solution of highly polluting sodium sulfide. This causes an increase in the sulfide content of the mill's effluent. On account of its toxicity the State Pollution Control Board prescribes a limit of 2ppm for sulfide in the treated effluent. Complying with these standards was one of the major problems
  • After dyeing the fabric, the dye is converted back to insoluble form with acidified dichromates to prevent washing out of the dye from fabric; dichromates are toxic too
  • Regulations are in place to enforce pollution control in almost all the countries including India
  • Chemical Substitution of these chemicals has been done and clean production was achieved and pollution control reached
  • Read more here

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