18
C. Gutiérrez-Bouzán et al.
Fig. 12 Examples of dyeings obtained reusing 70% of two exhausted reactive dyebaths (A and F)
both treated at 33 mA/cm 2 (versus a reference dyeing)
The quality of dyed fabrics was studied from colour differences (DE CMC(l:c) ) with
respect to references dyed with decalcified water. The difference in colour was determined in conformity with the Standard UNE-EN ISO 105-J03 [34]. The chromatic
coordinates and colour differences obtained with the effluents A and F are presented
in Table 3.
As can be seen, in all cases, the effluents were satisfactorily reused. All fabrics
showed colour difference values lower than 1, which is the a common acceptance
criteria established by many companies (DE cmc(2:1) < 1). It should be noted that the
treated effluents showed a colour removal rate of 80 and 72%, which demonstrates
that the full colour removal is not necessary for the effluent reuse. In general, 60–80%
colour removal can be an advisable value as an increasing of this rate will imply a
higher cost, but not always an improvement of reuse results.
A wide range of reuse trials have been made with the EC-UV system at 70%
and 100% reuse ratio, with effluents containing different types of residual reactive
Table 3 Colour differences obtained in dyeings with the reused effluents A and F
Effluent A
Dye
DH
DL
DC
DE cmc(2:1)
Yellow
0.32
−0.04
−0.64
0.72
Red
−0.59
0.64
−0.14
0.88
Navy
0.78
0.34
−0.29
0.90
Trichromie
−0.74
−0.52
−0.03
0.91
Effluent F
Dye
DH
DL
DC
DE cmc(2:1)
Yellow
0.05
−0.10
−0.38
0.39
Red
−0.13
−0.32
−0.09
0.36
Navy
−0.63
0.03
0.05
0.63
Trichromie
−0.53
0.52
0.07
0.74
C. Gutiérrez-Bouzán et al.
Fig. 12 Examples of dyeings obtained reusing 70% of two exhausted reactive dyebaths (A and F)
both treated at 33 mA/cm 2 (versus a reference dyeing)
The quality of dyed fabrics was studied from colour differences (DE CMC(l:c) ) with
respect to references dyed with decalcified water. The difference in colour was determined in conformity with the Standard UNE-EN ISO 105-J03 [34]. The chromatic
coordinates and colour differences obtained with the effluents A and F are presented
in Table 3.
As can be seen, in all cases, the effluents were satisfactorily reused. All fabrics
showed colour difference values lower than 1, which is the a common acceptance
criteria established by many companies (DE cmc(2:1) < 1). It should be noted that the
treated effluents showed a colour removal rate of 80 and 72%, which demonstrates
that the full colour removal is not necessary for the effluent reuse. In general, 60–80%
colour removal can be an advisable value as an increasing of this rate will imply a
higher cost, but not always an improvement of reuse results.
A wide range of reuse trials have been made with the EC-UV system at 70%
and 100% reuse ratio, with effluents containing different types of residual reactive
Table 3 Colour differences obtained in dyeings with the reused effluents A and F
Effluent A
Dye
DH
DL
DC
DE cmc(2:1)
Yellow
0.32
−0.04
−0.64
0.72
Red
−0.59
0.64
−0.14
0.88
Navy
0.78
0.34
−0.29
0.90
Trichromie
−0.74
−0.52
−0.03
0.91
Effluent F
Dye
DH
DL
DC
DE cmc(2:1)
Yellow
0.05
−0.10
−0.38
0.39
Red
−0.13
−0.32
−0.09
0.36
Navy
−0.63
0.03
0.05
0.63
Trichromie
−0.53
0.52
0.07
0.74