Nanoparticles for Sustainable Wastewater Treatment: Advances in Synthesis, Characterization, and Remediation Applications

• Nanoparticle synthesis, characterization, and wastewater applications systematically reviewed. • Structure–property–performance relationships governing contaminant removal elucidated. • Green and biogenic nanoparticle routes highlighted for sustainable remediation. • Scalability, environmental risks, and future research directions critically assessed. Currently, the demand for safe and clean water is increasing dramatically worldwide. Therefore, the recycling and reuse of wastewater effluents play a crucial role in supplementing the limited availability of clean water. To protect the environment and public health, wastewater treatment is a vital process. Therefore, it is essential to develop and implement advanced wastewater treatment methods that are both highly efficient and economical. Researchers have employed various innovative approaches for treating wastewater. However, Conventional methods for wastewater treatment are costly, require high energy consumption, and often require large land areas, making them unsuitable for many regions. To obtain desirable solutions to these problems, researchers have recently turned to the use of nanoparticles. Nanoparticles present a promising option for water treatment, offering their extensive surface area and improved chemical properties. Recent studies summarized in this review indicate that nanoparticle-based treatment systems frequently achieve removal efficiencies above 90 - 99% for heavy metals and more than 72 - 99.9% degradation efficiency for dyes and organic contaminants under optimized conditions. Despite ongoing research, our understanding in this domain remains relatively limited. This review provides a comprehensive knowledge of the synthesis routes, including physicochemical and green routes, characterization techniques, and the diverse classes of nanoparticles employed in wastewater remediation. Special emphasis is placed on zerovalent metals, metal oxides, carbon-based nanomaterials, and biopolymer-derived nanoparticles for removing toxic metals, organic contaminants, dyes, pharmaceuticals, and pathogens from polluted water sources. Reported studies further demonstrate that magnetic and photocatalytic nanoparticles enable rapid pollutant removal with improved recovery and reuse potential, enhancing process sustainability and reducing operational costs. This study also explores the prospective advancements in nanotechnology and the potential of nanoparticles in enhancing wastewater treatment efficiency, capitalizing on their unique surface properties, chemical characteristics, and tunable surface modification. Overall, nanoparticle-assisted treatment approaches show strong potential for scalable wastewater remediation with reduced treatment time and improved contaminant removal performance compared to many conventional systems. Through a comprehensive review of various classes of nanomaterials, this manuscript aims to explain the advancements in nanotechnology for wastewater management, thereby contributing to knowledge in this field and offering insights into sustainable and cost-effective wastewater treatment strategies.