Emerging nanotechnologies in adsorption of dyes: a comprehensive review of carbon and metal oxide-based nanomaterials

With the growing global population and rapid industrial expansion, the demand for clean water has significantly surged. Major pollutants, such as textile dyes, heavy metals, sewage, and industrial effluents, are increasingly contaminating the aqueous sources, posing significant threat to the public health and to the entire eco-system. Traditional water treatment methods are struggling to meet this demand due to rising operational costs. To safeguard natural water bodies, efficient strategies are required to control and mitigate pollution. The groundbreaking discovery of nanomaterials, as one of the most versatile materials, and their broad applications across various industries have spurred researchers to explore further modifications to enhance their performance. Among these, carbon-based and metal-oxide based nanomaterials have emerged as highly efficient due to their abundant availability, efficiency, and cost-effectiveness compared to other types of nanomaterials. This review focuses on the increasing prevalence of contaminants, advancements in treatment technologies, and the role of adsorption as a key approach for the removal of contaminants. It highlights the various synthetic strategies and potential of nanomaterials, particularly carbon-based and metal oxide-based nano-adsorbents, in effectively treating dye-contaminated wastewater, offering advanced and cost-effective solutions for water purification. Additionally, this article provides a comprehensive discussion on multitude of aspects encompassing the adsorption kinetics and isotherms, while emphasizing on the different operating parameters associated with the adsorption process and the regenerability of the fabricated adsorbents. Dedicated sections focused on the real-world applications, environmental fate and toxicity, and economic feasibility of these nanomaterials have been extensively presented. Finally, the challenges associated with the practical implementation of these nano-adsorbents, as revealed in the literature, have been addressed, proposing ways for future advancements for addressing these challenges.