Direct dyes are water-soluble anionic dyes. They can dye cellulosic fibers—such as cotton, linen, viscose, and Lyocell—directly under neutral or weakly alkaline conditions, without the need for mordants or fixing agents. Thanks to their advantages of simple application, cost-effectiveness, a complete color spectrum, and rich shades, direct dyes have long held a significant position in the textile dyeing, printing industry,paper coloring and leather dyeing.