Textile Dyes and Their Impact on the Natural Environment

Colours are the most important component of the textile and printing industries. These industries use different types of colouring materials to give attractive colours to clothes and prints. These colouring agents are called dyes. These dyes can be natural or synthetic. As natural dyes are present in limited colours and amounts, demand for synthetic dyes has increased many folds in recent years. Their use has increased because these are available in many colours at a reasonable price. These dyes are used in all the sectors of textile dyeing and printing industries. The natural dyes were nontoxic and harmless to human and the environment. But synthetic dyes are toxic and hazardous to the human and the environment. The pollution caused by dyes is called dye pollution. The effluents from dying and printing industries may contain toxic compounds like sulphur, nitrates, acids, heavy metals, and other materials which are used as colouring agents during the process. These dyes and colouring agents are released into water and are the major cause of high level water pollution. Printing inks contain heavy metals like titanium oxide, chromate, and iron which can cause groundwater pollution. Textile industries not only cause water pollution, but they also cause air pollution, noise, and thermal pollution. Dying and printing industries produce various gases like CO2, NO2, SO2, etc. in high amounts causing air pollution. Because of high thermal and photostability, dyes remain for a longer duration in the environment and cause harmful effects on humans and other organisms. Effects of dye pollution may include cancer, skin diseases, respiratory diseases, and eye irritation. Dye pollution can be mitigated by using modern techniques which may include physical, chemical, and biological treatments using absorbents.