Until the middle of the 19th century, all dyes came from natural sources, but the evolution of organic chemistry made it possible to produce synthetic dyes. Since then, developments in various fields of science have contributed to over 100,000 dyes that are used for a wide variety of applications such as textile dyes, printing inks and paint pigments. The major sources of release into the environment are however textile and dyestuff industries.

Dyes are classified according to their application and chemical structure. They are composed of a group of atoms responsible for dye color, called chromophores, as well as electron withdrawing or donating substituents that cause or intensify the color of the chromophores, called auxochromes. There are about 12 classes of dyes based on their chromophore, the most common being the azo group, followed by the anthraquinone group. A second classification of dyes is based on their mode of application to textiles and distinguishes acid, reactive, metal-complex, disperse, vat, mordant, direct, basic and sulfur dyes.

The dyes studied in this project are reactive triazine dyes. Reactive dyes can contain any chromagen. Reactive triazine dyes are widely used in industries to colour cotton and wool. The triazine groups of reactive dyes contain chlorines which are easily displaced in the dye bath whereby the dye molecule reacts with fibers to form covalent bonds.