Advancements in green-synthesized transition metal/metal-oxide nanoparticles for sustainable wastewater treatment: techniques, applications, and future prospects

In order to meet the demand for portable water and replenish depleting water resources caused by industrialization, urbanization, and population growth; wastewater purification has become crucial. Emerging contaminants (ECs), which include organic dyes, pesticides, pharmaceutical drugs, polyaromatic compounds, heavy metal ions, and fertilizers, among others, have caused significant disruptions to environmental balance and severe health complications. As a result, considerable effort has been devoted to the development of technologies that eliminate wastewater from effluents via adsorption, photocatalysis, and other means. However, considering the economic and environmental implications of the adopted technologies, green technology has gained significant attention owing to their eco-friendly approaches, cost-effectiveness, avoiding use of toxic and harmful chemicals and production of less-toxic by-products. Currently green-synthesized nanomaterials have seen tremendous growth in emerging as sustainable nanoadsorbents, nanocatalysts for the removal of the emerging contaminants from wastewater in highly efficient and eco-friendly manner. Thus, this review presents an overview of the various techniques utilized in wastewater treatment with a particular emphasis on the production and application of environmentally friendly transition metal/metal oxide nanoparticles as sustainable tools in wastewater treatment technology. This article also discusses the limitations and future potential of using green-synthesized transition metal/metal oxide based nanoparticles in advancing the technology on a broad scale.