Abstract:

Water scarcity is becoming a growing problem worldwide due to the expansion of industry, population growth and climate change, and the need for clean and potable water is becoming increasingly important. Traditional wastewater treatment techniques such as sedimentation, filtration, and chlorination often fail to remove emerging contaminants (ECs), such as pharmaceuticals, microplastics, heavy metals, and sometimes create toxic byproducts. Thus, nanotechnology has come up as a novel solution with materials of incredible surface area, tunable reactivity and adsorption capacities. In recent years, a paradigm change towards sustainability has led to the creation of "green" or biogenic nanomaterials. The green nanomaterials are synthesized from renewable biological resources like plant extracts and microbial consortia, which reduce environmental footprints, the use of hazardous chemicals and provide cost-effective remediation. The present review covers all the recent developments in the use of green nanomaterials such as metal/metal oxide nanoparticles (Ag, TiO₂, Fe₃O₄, ZnO), carbon-based nanostructures and bio-inspired nanocomposites in wastewater monitoring and remediation. Systematically, the main mechanisms of contaminant removal, such as physical adsorption, chemical adsorption, photocatalytic degradation, electrochemical reduction and advanced membrane filtration are explored. In addition, the incorporation of very sensitive nanosensors for real-time environmental monitoring is discussed. Recent computational methods, such as Molecular Dynamics (MD), Density Functional Theory (DFT), and Machine Learning (ML), are emphasized as key tools to translate experimental design into application, and to predict the efficacy and toxicity of nanoparticles. Finally, this review critically examines the issues of scalability, economic viability and nanotoxicity, and outlines the path for sustainable implementation of nanotechnology in water management on a global scale.

Graphical Abstract: Comprehensive framework for green nanomaterials in wastewater treatment, illustrating synthesis pathways from biological sources, removal mechanisms, and a critical overview of benefits, limitations, and future applications. Reproduced from Sustainable Chemistry for the Environment 10 (2025) 100238, under the Creative Commons CC BY‑NC‑ND 4.0 licence (http://creativecommons.org/licenses/by-nc-nd/4.0/) [1].

Keywords:

Environmental Sustainability, Sustainable Development, Renewable Energy, Climate Change, Circular Economy, Energy Efficiency, Environmental Protection, Mathematical Tools

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