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
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