Sustainable adsorption technologies for textile dye removal: Advances in biomass-derived and magnetically modified activated carbons

Dye pollutants are a major environmental concern, largely due to their widespread discharge from textile and related industries. Once released into aquatic systems, these dyes significantly deteriorate water quality by reducing light penetration, disrupting photosynthetic activity, and posing toxic risks to both aquatic organisms and human health. As a result, the effective removal of dyes from wastewater is essential for protecting the environment and safeguarding public health. Among the various treatment options available, adsorption has gained prominence as a particularly effective, simple, and eco-friendly method. This review provides an in-depth and comprehensive examination of textile dyes and the various contemporary strategies employed for the treatment of dye-polluted wastewater, with particular focus on adsorption-based methods. It thoroughly explores the key factors affecting the efficiency of the adsorption process, including solution pH, initial dye concentration, contact time, temperature, and the physicochemical characteristics of the adsorbent material. Special attention is given to understanding how these parameters interact to optimize dye removal performance and enhance the sustainability of wastewater treatment practices. Special attention is given to low-cost adsorbents derived from biomass waste, including pretreatment strategies that can significantly improve their adsorption performance. The review also explores regeneration methods aimed at enhancing the sustainability and cost-effectiveness of the adsorption process. A dedicated section focuses on magnetic adsorbents, which offer the combined advantages of high adsorption efficiency and easy recovery from aqueous solutions using an external magnetic field. Various types of magnetic materials are examined, including their synthesis, characterization, and performance under different operating conditions. Finally, the review outlines current challenges and highlights future research directions for optimizing magnetic adsorption technologies in practical wastewater treatment applications.