Elimination of dyes by catalytic reduction in the absence of light: A review

Developing novel technologies for the effectual treatment of wastewater comprising contaminated organic pollutants is of extraordinary importance across the globe. In the last few years, removal of organic pollutants using various nanocatalysts from aqueous solution by chemical reduction in the presence of NaBH 4 , as a reducing agent, has become an established route. Nanomaterials show great potential for the improvement of water treatment technologies. Recently, catalytic reduction of dyes by using various nanoparticles has received significant attention due to their effectiveness in degradation and producing less toxic and environmentally benign products. Herein, this comprehensive review discusses the classification of nanocatalysts, mechanisms involved in catalytic degradation of various types of dyes, recyclability of nanocatalysts and characterization techniques for various nanocomposites. We aim to review and summarize the recently published literature and R&D progress in catalytic reduction of various water pollutants. Different nanocatalytic assemblies used for reduction of dyes and their division based on nature of nanoparticles and composition of supporting materials have been described critically. A mechanism for chemical reduction of nitrophenols, methylene blue, Congo red, and methyl orange in the presence of nanocatalysts has been elaborated in this study.