Cleaner Technology Transfer to the Polish Textile ... - Miljøstyrelsen
Cleaner Technology Transfer to the Polish Textile ... - Miljøstyrelsen
Cleaner Technology Transfer to the Polish Textile ... - Miljøstyrelsen
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Topic 28.<br />
Neutralization after dyeing<br />
Case illustration:<br />
Use only neutralization after<br />
reactive dyeing of cot<strong>to</strong>n<br />
when needed<br />
Concept After dyeing in <strong>the</strong> alkaline range, it is normal <strong>to</strong> neutralize. Typically, acetic<br />
acid is used giving a contribution <strong>to</strong> COD in <strong>the</strong> waste-water. Acid is added <strong>to</strong><br />
assure that dyes are not washed out from fibres, e.g. in <strong>the</strong> first rinse after dyeing<br />
with certain reactive dyes. However, often <strong>the</strong>re seems <strong>to</strong> be no need for<br />
this acid addition. Alternatively, formic acid – or an even better mineral acid<br />
like diluted hydrochloric acid – could be used giving a smaller or no contribution<br />
of COD. This is documented in detail in a paper in Part 3.<br />
Improvement potentials Chemical savings. Reduction of COD load.<br />
Relevance Most companies.<br />
46