Environmental Engineering Reference
In-Depth Information
oxygen or hydrogen peroxide as a chemical oxidant. This enzymatic pro-
cess has a number of advantages over conventional physical, chemical and
biological processes [15-17].
This chapter provides a comprehensive literature review on the enzy-
matic treatment of various synthetic dyes and discusses the recent progress
and challenges associated with this technology. In addition, the fungal treat-
ment of synthetic dyes and contaminated effluents, as well as the enzymol-
ogy of the key ligninolytic enzymes, are covered in this chapter to explore
the important roles of fungal enzymes in synthetic dye decolorization.
More than 70 different synthetic dyes with various chemical structures,
including anthraquinone, azo (including diazo, triazo, and poly-azo), het-
erocyclic, indigoid, triarylmethane, and phtharocyanine dyes, are covered.
The chemical structures of most of the dyes discussed in this chapter are
drawn and presented in a consistent and legitimate format to aid the read-
ers' comprehension of different enzyme-substrate (i.e., dye) reactions. In
addition, the basic characteristics of textile dyes, including nomenclature,
chemical structures, and environmental impacts are briefly discussed.
6.2
Textile Dyes - Classifications, Chemical
Structures and Environmental Impacts
6.2.1
Classification of Dyes
More than 10,000 different dyes with a variety of colors and chemical
structures are commercially available around the world. A majority of the
dyes currently used are synthetic organic compounds, while some are of
natural origins and inorganic pigments based on minerals. These synthetic
and natural dyes may be classified in many ways such as their modes of
application, chemical structures, and colors [1]. Like any other commercial
chemicals such as solvents, pesticides, and pharmaceuticals, a dyestuff may
have many different names, ranging from common chemical names and
the International Union of Pure and Applied Chemistry (IUPAC) name
to generic and trade names. A comprehensive database of commercial
dyes and pigments called Colour Index International is maintained by the
Society of Dyers and Colourists and the American Association of Textile
Chemists and Colorists. Colour Index International contains 27,000 indi-
vidual products under 13,000 Colour Index (C. I.) Generic Names and
Colour Index Constitution Numbers, according to the Colour Index
International's website (http://www.colour-index.com/). The C. I. generic
name of a dye consists of its recognized usage class (e.g., direct, reactive,
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