Environmental Engineering Reference
In-Depth Information
Table 9.2
Characteristics of typical dyes used in textile dyeing operations
[17-20].
Ty p e of
Dye
Description
Example
Typical Pollutants
Associated with
Various Dyes
Acid
Dyes
Water-soluble anionic
compounds
Methyl
Orange,
Congo Red
color; organic acids;
unfixed dyes
Basic
Dyes
Water-soluble, applied
in weakly acidic
dyebaths; very
bright dyes
Methylene
Blue,
Malachite
Green
Degradation by physical,
chemical or biological
treatments may pro-
duce small amount of
toxic and carcinogenic
products
Direct
Dyes
Water-soluble, anionic
compounds; can be
applied directly to
cellulosics without
mordants (or metals
like chromium and
copper)
Congo Red
and Matius
Ye l l o w
color; salt; unfixed dye;
cationic fixing agents;
surfactant; defoamer;
leveling and retarding
agents; finish; diluents
Disperse
Dyes
Not water-soluble
Pink B and
Blue B
color; organic acids;
carriers; leveling agents;
phosphates; defoamers;
lubricants; dispersants;
delustrants; diluents
Reactive
Water-soluble, anionic
compounds; largest
dye class
Procion dyes
color; salt; alkali; unfixed
dye; surfactants;
defoamer; diluents;
finish
Sulfur
Organic compounds
containing sulfur or
sodium sulfide
Alizarin
color; alkali; oxidizing
agent; reducing agent;
unfixed dye
Vat
Water-insoluble; oldest
dyes; more chemi-
cally complex
Indigo, Tyrian
Purple
color; alkali; oxidizing
agents; reducing agents
groups, they are resistant to breakdown by chemical, physical and biologi-
cal treatments [27]. They cause allergic reactions, dermatitis, skin irrita-
tion, mutations, and cancer [28]. Some of the adsorption studies by clay
minerals have been carried out on crystal violet [28], methylene blue [29],
and basic yellow 28 [30].
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