Recent trend on engineered nanostructured photocatalyst toward rapid degradation of cationic dyes: A review

The presence of inorganic and organic pollutants into water environment has become global serious concern. The wastewater discharged from food, textiles, leather, plastic, paper, cosmetic and pharmaceutical industries introduce both cationic and anionic dyes in natural and synthetic forms into the water bodies. Cationic dyes are considered more toxic and problematic in wastewater than anionic dyes due to their positive charge which strongly binds to the negatively charged biological molecules leading to greater cellular damage, possible carcinogenicity and environmental persistence, thus, posing major threats to aquatic life and human health. Several conventional processes have been utilized for the degradation of cationic dyes, among which photocatalysis using nanomaterials and nanocomposites stands out as a promising technology. These nano-based structured materials with properties of semiconductor are excellent photocatalyst both under UV and visible light radiation. This present review discussed the recent advances in performance of various critically assessed reported nanomaterials in degradation of cationic dyes. A detailed evaluation of articles published on photocatalytic degradation of toxic cationic dyes was presented depicting different functionalization strategies, architectural structures of the nanostructured materials. Photocatalytic performance, degradation mechanism and stability of the nano-based catalyst were also outlined extensively. In addition, limitations and future outlook were discussed with a focus on the development of novel strategies to further improve the effectiveness and sustainability of nanostructured photocatalysts for cationic dye degradation. This review presents a significant perspective on existing studies towards efficient photocatalytic degradation of cationic dyes using nanocomposites due to increase in pollution of water ecosystem. Also, the review will guide the future researchers to find solutions to environmental problems and sustainable wastewater management.