Current Developments in Chitosan‐Based Hydrogels for Water and Wastewater Treatment: A Comprehensive Review

Abstract The global shortage of fresh water is a critical issue, especially in regions with limited rainfall. Developing reliable water and wastewater treatment technologies is urgent. Among the available methods, adsorption stands out as a highly effective, straightforward, and cost‐efficient approach. It avoids the use of additional chemicals and reduces the risk of contaminating water source with undesirable by‐products. Chitosan (CS)‐based hydrogels have gained attention for their excellent adsorption capacities for pollutants and water. These materials are also known for their bioavailability, biocompatibility, biodegradability, cost‐effectiveness, and environmental friendliness, making them promising candidates for water and wastewater treatment. This comprehensive review explores recent advancements in the use of CS‐based hydrogels for various applications, including pollutant removal, oil‐water separation, seawater desalination, and atmospheric water condensation. It highlights the benefits of this material in wastewater treatment, providing a broader understanding of their potential for the research community. The review also focuses on the synthesis and modification techniques of these hydrogels, such as cross‐linking, grafting, and ion imprinting, which significantly enhance their adsorption performance and mechanical stability. Additionally, the challenges faced by CS‐based hydrogels in practical applications are discussed, along with potential solutions. The paper concludes by forecasting future directions in this field, offering valuable insights for researchers. Overall, this review provides a comprehensive overview of the current state of the art of CS‐based hydrogels for water treatment applications, offering valuable insights into their effective utilization for water and wastewater treatment, and emphasizing their potential to address global water pollution challenges.