Nanomagnetic carbon-based adsorbents for intensifying dye uptake from wastewater (a review study)

Dye pollutants are among the most persistent and harmful contaminants in water systems, originating from a range of industrial processes and posing serious risks to both human health and ecosystems. Effective removal of these pollutants is an ongoing environmental challenge. While multiple techniques have been developed to tackle dye contamination, adsorption stands out due to its reversibility, operational simplicity, and high efficiency. The key to success lies in the choice of adsorbents, with magnetic carbon-based materials (such as activated carbon, carbon nanotubes, graphene oxide, and biochar) gaining prominence for their unique blend of performance and cost-effectiveness. These materials, enhanced by the synergistic interaction between magnetic particles and carbon matrices, offer superior adsorption capabilities not only for dyes but also for other organic contaminants. This review explores the sources and environmental impacts of dye pollutants, along with various wastewater treatment methods. A particular focus is placed on magnetic carbon-based adsorbents, highlighting their potential for large-scale industrial application due to their ease of modification, cost-efficiency, and ability to prevent secondary pollution. Carbon-based materials with three-dimensional structures show significant promise as they facilitate easier recovery and reuse, making them ideal for sustainable dye removal. The review also provides an in-depth analysis of adsorption kinetics, equilibrium, and thermodynamics in dye removal. Notably, magnetic biochar and nZVI/BC composites have demonstrated outstanding removal efficiencies of 99.8 % and 99.9 % for Acid Orange 7 and Malachite Green dyes, respectively. These findings underscore the potential of magnetic-carbon composites to revolutionize water treatment technologies, offering a path toward more effective and environmentally friendly solutions.