Colorants in Health and Environmental Aspects
The environmental characteristics of colorants (dyes and pigments) cover the topics pertaining to the impact of such compounds on human health and the environment. Effluent aqueous waste containing dye compounds causes serious problems. Manufacture and use of synthetic dyes for fabric dyeing has therefore become a massive industry today. Consequently, they have become common industrial environmental pollutants during their synthesis and later during fiber dyeing. This is main requirement for the innovations in the related processes as well as the investigation of appropriate and environmentally friendly treatment technologies. Use of synthetic dyes has an adverse effect on all forms of life. Presence of sulphur, naphthol, vat dyes, nitrates, acetic acid, soaps, enzymes chromium compounds and heavy metals like copper, arsenic, lead, cadmium, mercury, nickel, and cobalt and certain auxiliary chemicals all collectively make the textile effluent highly toxic. Dyes have various effects on human health depending on the application area. Skin irritation and contact dermatitis have been reported for some synthetic dyes and the use of azo dyes made from carcinogenic amines has been banned by legislation in many countries. The researches on alternative and innovative wastewater treatment techniques have focused especially on the use of biological materials. Adsorbents such as activated carbon, zeolite and diatomite have been used as efficiently for cleaning by adsorption of colored wastewaters. In this chapter, a wide range of dyes and pigments are discussed in the context of green chemistry with environmental and health aspects by considering their negative results related with their use.