Removal of Synthetic Textile Dyes From Wastewaters: A Critical Review on Present Treatment Technologies

Azo dyes represent the largest class of industrial colorants. These are no longer used only for the coloration of textiles, plastics, paints, inks, and lacquers, but rather serve as key components in high-tech applications such as optical data storage, reprographics, display devices, dye-sensitized solar cells, energy transfer cascades, light-emitting diodes, laser welding processes, or heat management systems. Azo dyes are also of growing importance in the medical and biomedical fields. In most of these applications, the color is largely irrelevant and it is the ability of the colorants to absorb visible electromagnetic radiation with high efficiency, or other functional property, that is exploited. With the…