Mesoporous-assembled nanocrystal photocatalysts for degradation of azo dyes

Abstract

Currently, azo dyes undoubtedly play a significant role in our daily life since they are used for coloring several kinds of products ranging from garments, furniture, to large equipment in various industries. Unfortunately, they are carcinogenic compounds when being exposed to human beings and living organisms. When these carcinogenic compounds are processed in various industries to manufacture the aforementioned products, they are inevitably released to environment as the main components in the effluent wastewaters. Therefore, various basic and advanced techniques have been developed to treat and eliminate these compounds from the effluent wastewaters. During the last decades, a multitude of research attempts have been extensively devoted to investigate advanced oxidation processes (AOPs) as a highly potential technique for wastewater treatment. Among the investigated AOPs, heterogeneous photocatalysis is greatly considered to be the most promising destructive technique for treatment of wastewaters containing several types of azo dyes. For this technique, various nanostructured photocatalysts, especially with TiO2-based compounds, can be efficiently applied as they possess chemically stable and photo-stable characteristics. Therefore, this chapter summarizes sequentially the significance of azo dyes, their removal techniques when they are released to environment with an emphasis on the photocatalytic process, and the application of nanostructured photocatalysts for the photocatalytic process. The main focus of this chapter is also to describe how to synthesize mesoporous-assembled nanocrystal photocatalysts with very unique properties and their application for degradation of azo dyes in wastewaters.