Research Progress on Photocatalysts for Degradation of Organic Pollutants in Printing and Dyeing Wastewater

Abstract

Dye-containing wastewater, largely discharged from the textile or printing industries, is one of the well-known sources of water pollution, posing great threats to both human health and the living environment. Although several water treatment technologies including physisorption, chemical oxidation, and biodegradation have been developed, most of them are costly and may produce some by-products with unknown toxicities. Therefore, it is highly desirable to develop economic and effective treatment technologies to reduce water resource consumption and protect the environment. Photocatalysis is a method in that highly reactive transitory species such as superoxide or hydroxyl radicals can be generated by reacting oxygen or water with photocatalysts upon irradiation of light, then degrading the organic dyes. Because the whole photocatalysis process has no chemical input and no secondary pollutants, it is considered to be an environmentally friendly, energy-efficient, and sustainable technique. In this paper, we have reviewed different kinds of photocatalyst systems developed in recent ten years for the degradation of organic pollutes, which cover inorganic semiconductors, metal-organic frameworks, organic small molecules, and conjugated porous polymers. Based on the large surface area and high photocatalytic activity, the conjugated porous polymers can simultaneously adsorb and photodegrade organic dyes under visible light, exhibiting stronger developmental potential compared with other photocatalytic materials.