Uranium removal from environmental water and nuclear waste: Nanomaterial solutions and their environmental sustainability

• Nanomaterial-based extraction methods offer a promising means of removing and recovering uranium from a variety of aqueous streams. • Nanomaterials have high adsorption capacity, dense active sites, excellent selectivity, and are easy to reuse. • This review examines a wide range of nanomaterials, including carbonaceous, magnetic, functionalized, silicon-based, metallic oxide/hydroxide nanomaterials and bio-nanocomposites. • The challenges and opportunities associated with employing nanomaterials for uranium separation are discussed detail. • The stability (chemical, thermal, and mechanical) and toxicity of nanomaterials are important concerns. • The sustainability and transformation of nanomaterials in aquatic and terrestrial environments are analysed in depth. The separation and extraction of uranium from mining waste water, contaminated surface water and groundwater, and even from seawater hold significant importance in various applications. Nanomaterial-based extraction methods have been quickly developing and offer a promising means of removing and recovering uranium from a variety of aqueous streams. Nanomaterials possess distinct advantages such as high adsorption capacity, dense active sites, ease of reuse, and excellent selectivity. In this comprehensive review, we conduct an in-depth examination of a wide range of nanomaterials, including carbonaceous, magnetic, functionalized, silicon-based, and metallic oxide/hydroxide nanomaterials, each exhibiting diverse morphologies. Additionally, we offer detailed discussions on mixed oxides and bio-nanocomposites. Carbonaceous nanomaterials demonstrate superior chemical stability in strongly acidic nuclear wastewaters than common inorganic sorbents like hydroxyapatite and hydrous oxides. Furthermore, they are more resilient to radiation and thermal conditions than organic exchange resins. Extraction using recyclable functionalized magnetic nanomaterials offers high selectivity and reduces the complexity of the required equipment. We delve into the challenges and opportunities associated with employing nanomaterials for uranium separation, discussing them in detail. The control of their structures and the stability (chemical, thermal, and mechanical) and toxicity of nanomaterials are important concerns. Finally, we perform an in-depth analysis of the environmental sustainability of nanomaterials. These materials can enter aquatic and terrestrial environments through direct industrial discharges, wastewater effluents, surface runoff, and indirectly via land-applied products like sludges or biosolids. Once in the environment, nanomaterials undergo transformations influenced by their properties and the surrounding medium, involving processes like aggregation, dissolution, and redox reactions.