Abstract:
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In this work, the feasibility of reusing water and salt from reactive dyebaths after electrochemical
decolourization was evaluated. Dyeing series of ten reuses with three reactive dyes
(Navy Blue Procion H-EXL, Crimson Procion H-EXL and Yellow Procion H-EXL) were
carried out (individually and in a trichromie) and color differences and total organic carbon
values were measured to study how the successive reuses affect the quality dyeing. The first
reuse produced dyeings with low colour differences with respect to a standard dyeing. In
the subsequent reuses, colour differences increased until they reached a constant value at the
4th or 5th reuse, following a similar behavior to the organic matter content. At this point, it
is determined the percentage of dye increase that allows for continuous dyeing of acceptable
quality for the textile industry. To obtain dyeings with acceptable color differences (DE
⁄
CMC
(2:1) 6 1) independent of the number of consecutive reuses, a 30% increase in blue dyestuff
and 10% for red dyestuff must be added, whereas in the case of yellow dyeing, it was not
necessary to increase the dye amount after subsequent reuses. In each dyeing, this process
allowed savings of 70% of water and an average of 60% for salt. |