Unlocking the potential of biosynthesized zinc oxide nanoparticles for degradation of synthetic organic dyes as wastewater pollutants

Abstract

The azo dyes released into water from different industries are accumulating in the water bodies and bioaccumulating within living systems thereby affecting environmental health. This is a major concern in developing countries where stringent regulations are not followed for the discharge of industrial waste into water bodies. This has led to the accumulation of various pollutants including dyes. As these developing countries also face acute water shortages and due to the lack of cost-effective systems to remove these pollutants, it is essential to remove these toxic dyes from water bodies, eradicate dyes, or generate fewer toxic derivatives. The photocatalysis mechanism of degradation of azo dyes has gained importance due to its eco-friendly and non-toxic roles in the environment. The zinc nanoparticles act as photocatalysts in combination with plant extracts. Plant-based nanoparticles over the years have shown the potential to degrade dyes efficiently. This is carried out by adjusting the dye and nanoparticle concentrations and combinations of nanoparticles. Our review article considers increasing the efficiency of degradation of dyes using zinc oxide (ZnO) nanoparticles and understanding the photocatalytic mechanisms in the degradation of dyes and the toxic effects of these dyes and nanoparticles in different tropic levels. HIGHLIGHTS The review focuses on green synthesis of metallic ZnO nanoparticles.; Dye degradation by greener and cost-effective approach is the need for many developing countries.; Green synthesised ZnO nanoparticle photocatalysis mechanism is reviewed comprehensively.; Toxicity of dyes and ZnO nanoparticles at tropic levels is highlighted.;

Keywords

• azo dyes
• dye degradation
• green synthesis
• nanoparticle
• toxicity
• water pollution