With the development of photocatalytic technology, it has characterized the mild reaction conditions, thorough degradation, clean and environmental protection in environmental purification, and gradually become one of the hot technologies in the field of pollution control. Bi₂WO₆ has become a hot research focus in the field of visible light photocatalysis because of its high visible light activity.

With the rapid development of chemical industry such as pesticides, dyestuff, petrochemical industry, environmental pollution is becoming more and more serious. Among them, printing and dyeing wastewater has become one of the most important sources of water pollution. There are many kinds of dyes and auxiliaries, and most of them are difficult to degrade. Some of them also contain carcinogen, such as benzene ring, amine group, azo group and so on. All these have added difficulty to the treatment of dye wastewater.

Photocatalytic oxidation of tungsten trioxide / iron composite photocatalyst is undoubtedly one of the most promising technologies in the world today. It shows the application of solar energy in many aspects, such as photolysis of water, access to hydrogen energy, and treatment of polluted wastewater.