Multifunctional adsorbable chitosan-based hydrogels: Towards efficient and multifunctional green solutions for pollution management

Chitosan-based hydrogels (CSHs), as an environmentally friendly material with excellent biocompatibility and biodegradability, have shown great potential for application in the treatment of water pollutants. This review systematically summarizes the general characteristics, adsorption mechanisms, and multifunctional applications of CSHs. First, the physicochemical properties of CS and its hydrogels are analyzed, with a particular emphasis on their unique three-dimensional network structure, adjustable physicochemical properties, and good water absorption capacity. Then, the complex and diverse adsorption mechanisms of CSHs are introduced, including electrostatic interactions, complexation, hydrogen bonding, π-π interactions, ion exchange, and chemical reactions, with special emphasis on the synergistic effects of these multiple mechanisms that enable the hydrogels to effectively treat various pollutants. In addition, the important applications of CSHs in the adsorption and removal of heavy metal ions, organic pollutants, dye wastewater, microplastics, antibiotics, endocrine disruptors, and oil/water separation from water are discussed. Finally, a comprehensive outlook on the future development of CSHs is provided, including the exploration of low-cost and high-efficiency production processes, enhancement of the mechanical strength of hydrogels, and the development of recycling and reuse technologies to achieve their widespread application in sustainable development. Through continuous technological innovation and multidisciplinary collaboration, CSHs are expected to play a greater role in future environmental protection efforts and make a positive contribution to the creation of a cleaner and more harmonious living environment.