Systematic Review of Chitosan-Based Adsorbents for Heavy Metal and Dye Remediation.

Water contamination from heavy metals and synthetic dyes presents a persistent environmental challenge, necessitating the development of efficient and sustainable remediation strategies. This review critically evaluates chitosan-based adsorbents, focusing on chitosan-activated carbon composites, and explores recent breakthroughs in structural and functional modifications that enhance their adsorption capacity. Innovations such as nanoparticle integration, Metal-Organic Frameworks (MOFs), bio-based reinforcements, and surface functionalization have significantly improved selectivity, adsorption kinetics, and regeneration potential, enabling greater adaptability for wastewater treatment. Additionally, this review highlights the emergence of hybrid water treatment technologies, including adsorption-assisted photocatalysis, electrochemical regeneration, and nanostructured filtration systems, which offer promising solutions for overcoming challenges related to adsorbent stability, scalability, and process efficiency in complex wastewater matrices. The study comprehensively evaluates these advancements, offering insights into material innovations, process optimization strategies, and their alignment with circular economy principles for sustainable water treatment applications. Future research should prioritize enhancing long-term adsorbent stability, improving regeneration efficiency, and integrating predictive modeling techniques to bridge the gap between laboratory advancements and large-scale implementation.