Photocatalytic degradation of dyes in textile effluent: A green approach to eradicate environmental pollution

Abstract Dyes are a major class of organic compounds which find a multitude of applications in human life. The dyes belong to mostly synthetic organics and are toxic, nonbiodegradable, and resistant to direct degradation by sunlight and, therefore, they remain as persistent pollutants. The removal of these nonbiodegradable organic chemicals from the environment is a crucial ecological problem. Some common techniques, such as adsorption using activated carbon, flocculation, electrocoagulation, UV light degradation, and redox treatments, are being routinely used for abating dyes. In the present scenario, due to the incompetence of the techniques in one way or the other, there is requirement of improved wastewater treatment measures. Green-synthesized metallic nanoparticles, being nontoxic, inexpensive, and stable under ambient conditions, are ideal to be used for clean technology. In recent past efforts have been done to develop metal nanoparticles with high photocatalytic activities for their application in solving environmental problems. The significant photocatalytic performance of metallic nanoparticles is originated mainly due to the presence of surface proteins which act as an effective host for dyes and facilitates absorption of dye. The approach is highly advantageous as it does not yield toxic intermediate products, making it suitable for cleaning polluted water bodies that contain low to medium concentration of contaminants. Only a handful of studies have been made in this field and hence the noble metals have been widely implemented as promising candidates for the photocatalytic degradation reactions of dyes such as methyl violet, safranin, eosin methylene blue, and methyl orange.