Insights and perspectives of chitosan-based hydrogels for the removal of heavy metals and dyes from wastewater.

Water pollution has become an increasingly serious issue, necessitating the design and development of more effective wastewater treatment methods. Chitosan-based hydrogels, owing to their unique structural and chemical properties, have demonstrated high efficiency in removing contaminants. However, the application remains restricted by the scarcity of effective adsorption sites and limited environmental stability. This review summarizes recent advances in the production of chitosan-based hydrogels and their application in the removal of heavy metals and dyes from wastewater. Various methods to improve the adsorption capacity of chitosan-based hydrogels for different heavy metals, anionic, and cationic dyes have been reviewed, and the adsorption mechanisms have been elucidated. In addition, the application of chitosan-based hydrogels for adsorption faces significant challenges, including sensitivity to pH change, the coexistence of multiple pollutants, and difficulties in recycling. This review outlines relevant strategies to overcome these challenges and aims to provide a reference for synthesizing novel, efficient, and environmentally friendly chitosan-based adsorbents. This review aims to offer new ideas and directions for addressing the issue of heavy metal and dye pollution in wastewater.