Emerging nanotechnology approaches for sustainable water treatment and heavy metals removal: a comprehensive review

Water pollution is a significant worldwide concern, caused mainly by industrialization, urban development, and inadequate waste management, leading to the release of harmful pollutants, especially heavy metals, into water bodies. These pollutants provide significant risks to ecological and public health owing to their toxicity, persistence, and bioaccumulative properties. Traditional water and wastewater treatment methods often inadequately remove these persistent pollutants due to challenges in selectivity, efficiency, and flexibility. Nanotechnology has grown as an effective and innovative method for eliminating pollutants, providing improved materials with distinctive physicochemical characteristics, including large surface area, increased reactivity, and functional tunability. The study systematically examines the utilization of nanotechnology in water and wastewater treatment, focusing on the adsorption-based elimination of heavy metal ions. The article begins with a summary of conventional treatment techniques and their limitations, then addresses adsorption principles, including physisorption and chemisorption processes. The review classifies and critically evaluates various types of nanoadsorbents, such as carbon-based nanocomposites, zeolites, metal and metal oxide nanoparticles, silica nanomaterials, polymer-based materials, metal-organic frameworks, and layered double hydroxides, emphasizing their efficacy under different operational conditions. Furthermore, essential nanomaterial characterization methods are introduced to assess structure-function relationships. This study provides an essential overview for academics and practitioners seeking to develop efficient, sustainable, and cost-effective nanomaterials for advanced water treatment systems by including current advancements and comparative data.