Recent progress in nanomaterial-based adsorption technologies for dye removal from wastewater.

Dye-contaminated wastewater from textile, printing, leather, paper, cosmetic, and related industries poses serious environmental and health risks due to the high stability, low biodegradability, and potential toxicity of synthetic dyes. Adsorption has emerged as a practical and efficient treatment method because of its simplicity, flexibility, high removal efficiency, and suitability for different dye classes under mild conditions. This review highlights recent advances in dye removal using advanced adsorbents, particularly nanoparticle-based materials, carbon-based adsorbents, polymers, biopolymers, metal-organic frameworks, and zeolitic imidazolate frameworks. Adsorption efficiency is mainly influenced by surface area, pore structure, surface charge, functional groups, adsorbent dosage, initial dye concentration, contact time, temperature, and solution pH. The main removal mechanisms include electrostatic attraction, hydrogen bonding, π-π interactions, ion exchange, surface complexation, pore filling, and coordination interactions. Most reported systems follow pseudo-second-order kinetics, while Langmuir and Freundlich isotherms are commonly used to describe equilibrium behavior. Despite promising laboratory results, practical application remains limited by high production cost, difficult separation, poor regeneration, reduced efficiency in real wastewater, and possible secondary pollution. Future studies should focus on low-cost, reusable, stable, eco-friendly, and scalable adsorbents, with greater attention to real effluents, toxicity assessment, regeneration, economic analysis, and pilot-scale validation.