Photochemical Treatments

http://www.intechopen.com/articles/show/title/photochemical-treatments-of-textile-industries-wastewater
Photochemical Treatments
of Textile Industries Wastewater
Falah Hassan Hussein
Chemistry Department, College of Science, Babylon University
Iraq
1. Introduction
Textile industry is one of the most water and chemical intensive industries worldwide due
to the fact that 200-400 liters of water are needed to produce 1 kg of textile fabric in textile
factories (Correia et al., 1994 & Orhon et al., 2003). The water used in this industry is almost
entirely discharged as waste. Moreover, the loss of dye in the effluents of textile industry
can reach up to 75% (Couto & Toca-Herrera, 2006). The effluents are considered very
complex since they contain salt, surfactants, ionic metals and their metal complexes, toxic
organic chemicals, biocides and toxic anions.
Azo dyes are regarded as the largest class of synthetic. Approximately, 50–70% of the
available dyes for commercial applications are azo dyes followed by the anthraquinone
group (Konstantinou & Albanis, 2004). Azo dyes are classified according to the presence of
azo bonds (–N=N–) in the molecule i.e., monoazo, diazo , triazo etc. and also sub-classified
according to the structure and method of applications such as acid, basic, direct, disperse,
azoic and pigments (Bhutani, 2008). Some azo dyes and their dye precursors are well-known
of high toxicity and suspected to be human carcinogens as they form toxic aromatic amines
(Gomes et al., 2003 & Stylidi et al., 2003).